uPVC Door Lock Repair
If your uPVC door is stiff to lift, the handle spins without engaging, the key turns but the door will not open, or the multi-point locking points simply refuse to shoot home, the gearbox or multipoint mechanism inside the door is almost certainly the cause. These mechanisms are under constant mechanical stress — every time you lift the handle and lock up, the internal cam and follower are cycling through their full range of motion. Over time, particularly on older Erith properties where doors may have been installed ten or fifteen years ago, the internal components wear, corrode, or crack, leaving the door either stuck fast or impossible to secure properly.
Open 24 hours, 7 days a week · Fully insured
“Erith Locksmiths is a fully insured, 24/7 mobile locksmith service covering Erith, Belvedere, and the surrounding DA8 and DA17 postcode districts. Our trained technicians come to you — no need to remove the door or transport anything. Whether it is a front door on a Victorian terrace in Erith town centre, a patio door in a garden flat near Erith Riverside, or a back door on a property close to Lesnes Abbey, we carry a wide selection of replacement gearboxes and multipoint mechanisms in the van so that the majority of repairs can be completed in a single visit.
What we do
Available 24/7
Day, night, weekends and bank holidays — a real local locksmith answers and sends a fully-stocked van.
We come straight away
Based in Erith, we send a locksmith straight away — we're usually with you in about 30 minutes.
Fully insured
Vetted locksmiths, a clear price on the phone, and no surprise add-ons when we arrive.
Damage-free entry
We pick and bypass locks the right way, so most lockouts are solved without drilling anything.
How a uPVC Multipoint Lock Mechanism Actually Fails
[3] The multipoint lock on a uPVC or composite door works by linking a central gearbox to a series of locking points — typically hook bolts, roller cams, and a deadlock — that all move simultaneously when you lift the handle and turn the key. The gearbox is the mechanical heart of this system: a cast housing containing a follower, a cam plate, and a series of springs and levers. When the gearbox fails, one of a handful of things usually happens. The handle lifts but nothing engages — the follower has sheared or the cam has cracked. The key turns freely but the door stays unlocked — the internal deadlock linkage has broken. The door locks but then springs open under pressure — a hook bolt has worn round and is no longer catching the keep. Sometimes a single locking point seizes while the rest function, putting uneven stress on the frame and making the door nearly impossible to close squarely.
These faults are especially common on sliding patio doors along the rear of Erith properties, where the bottom track collects grit from the garden and the mechanism is worked hard every day. A sliding door lock replacement on a patio door often involves not just the gearbox but also the keeps and strike plates embedded in the frame — components that are frequently overlooked but are just as critical to a secure, smooth-operating door. Our technicians assess the full system before recommending parts, so you are not paying for a gearbox only to find the door still rattles because a keep has shifted.
uPVC Door Lock Repair or Full Replacement — What You Actually Need
One of the most common questions we are asked when we arrive at a Belvedere or Erith property is whether the mechanism can be repaired or whether a full replacement is necessary. The honest answer depends on the specific fault and the age and condition of the existing hardware. A mechanism with a cracked cam plate or a sheared follower cannot be internally repaired on the doorstep — the gearbox must be replaced. However, if the problem is a stiff or misaligned door causing the locking points to miss their keeps, adjustment and lubrication may resolve the issue without any new parts at all. We carry both outcomes in mind when we diagnose, because unnecessary parts mean unnecessary cost, and we will tell you plainly which option applies before any work begins.
Where replacement is needed, we match the new gearbox to the existing door spec — backset, case size, and follower size all need to correspond exactly to the original, otherwise the handle spindle will not engage correctly or the faceplate will not sit flush. We stock mechanisms compatible with the most widely fitted multipoint lock brands found across Erith and Belvedere properties, and we can source less common sizes quickly. If the door is a composite rather than a standard uPVC profile, the mechanism type may differ, so our technician will confirm compatibility on-site. This attention to spec is what separates a lasting repair from one that fails again within months.
Front, Back, and Patio Door Lock Replacement Belvedere — What Changes Between Each
Front doors in Erith and Belvedere typically face the highest security demand. As well as the multipoint mechanism, most uPVC front doors use a euro cylinder, and cylinder condition matters enormously. If your euro cylinder shows signs of wear, or if the door has an older cylinder without anti-snap protection, we will flag this during the visit. A TS007 3-star anti-snap cylinder is worth considering at the same time as a gearbox replacement — it is a straightforward door lock installation that significantly raises the resistance of the door to a common forced-entry technique used on uPVC doors across south-east London. We confirm an exact up-front price before we begin, so you can decide with full information rather than a surprise at the end.
Back doors present a different set of challenges. Many Erith properties have uPVC back doors fitted with a simpler two-point or three-point mechanism rather than a full five or six-point system, and these are often the first to fail because they receive less attention and maintenance. French doors add further complexity — two interconnected leaves mean the mechanism on each door must align with a central astragal keep, and misalignment here is a frequent cause of doors that feel locked but can be pushed open under load. Patio sliding doors, as mentioned, have their own distinct mechanism: a hook-and-roller system that runs in a track, completely different from a hinged door gearbox. Knowing which type of door you have before we arrive means we can bring the right parts and complete the job in one call-out.
Calling Us Out — What Happens, What to Expect, and Local Context
When you call 020 3757 5599, we take a few details about the fault and the door type, confirm an exact price on the phone before anyone travels, and send a technician straight away. We are usually with you in about 30 minutes for addresses in Erith, Belvedere, and the immediate DA8 and DA17 areas — though travel time can vary depending on where in the area we are when you call. We operate every hour of every day, including bank holidays, evenings, and weekends, because lock faults do not follow a Monday-to-Friday schedule. If your door has failed in the locked position and you cannot leave the property, that is treated as an emergency and prioritised accordingly. For properties near Erith Quarry or along the Thames-side stretches of Bronze Age Way — areas we cover regularly — the same 24/7 response applies.
The final quote we confirm on the phone takes into account the door type, the specific mechanism needed, the time of day, and the travel distance from our nearest available technician. There are no hidden charges added after the work is done. Our technicians are trained, insured, and experienced specifically in uPVC and composite door hardware — they will explain what they found, show you the failed component, and walk you through the new mechanism before they leave. If you are a tenant, we are happy to explain the work carried out in a way that is easy to pass on to your letting agent or landlord. If you are a managing agent responsible for a block of flats in Belvedere with multiple uPVC doors, we can assess and report across multiple units in a single visit. Call 020 3757 5599 — we answer 24/7.
Quick Guide — Replacement, Installation, Repair, and Change: What Each Term Actually Means for uPVC Doors
These four words are often used interchangeably, but they describe different scopes of work and different costs. A repair means fixing what is already there — this applies when the fault is a minor misalignment, a worn keep, or a mechanism that just needs cleaning and lubrication. A replacement means removing the failed gearbox or multipoint strip and fitting a matching new component in the same position — this is the most common outcome for a broken uPVC mechanism. An installation refers to fitting lock hardware into a door that did not previously have it, or fitting a completely new door furniture set including handle, cylinder, and mechanism together — this is what happens on a new door or following significant damage. Changing the lock on a uPVC door most commonly means changing the euro cylinder rather than the entire mechanism — this is relevant after a break-in, a lost key, or a change of tenancy, and it is a quick process that leaves the existing multipoint mechanism untouched provided the mechanism itself is in good condition.
Understanding which category your situation falls into helps you have a clearer conversation when you call, and helps us bring the right parts first time. If you are unsure, describe what the door is doing — or not doing — and our team will work out the rest. We cover upvc door lock repair Belvedere and the wider Erith area every day, so these faults are familiar territory.
Frequently asked questions
My uPVC door handle lifts but the door will not lock — is this the gearbox?
Almost certainly, yes. When the handle lifts but the locking points do not shoot out, the internal cam or follower inside the gearbox has usually failed — either cracked or sheared. This is one of the most common faults we attend across Erith and Belvedere. The gearbox needs to be replaced rather than repaired in situ. We carry a broad range of replacement mechanisms in the van, so in most cases we can complete the work in a single visit. Call 020 3757 5599 and describe the symptoms — we will confirm whether parts are likely to be in stock before we travel to you.
How much does it cost to repair or replace a uPVC door lock mechanism?
We do not publish fixed prices because the final quote depends on several factors: the type of mechanism needed (gearbox size, case dimensions, number of locking points), whether the cylinder also needs attention, the time of day — evenings, weekends, and bank holidays affect the call-out element of the quote — and the travel distance from our nearest technician to your address. What we always do is confirm an exact price on the phone before anyone travels, so you know precisely what you are agreeing to. There are no additional charges once the work is done.
Can I replace a uPVC door gearbox myself?
The replacement itself is a mechanical job involving removing the door furniture, sliding out the old multipoint strip or gearbox cassette, and fitting a correctly specced replacement. The main difficulty is matching the new part to the original — backset, follower size, case height, and fixing centres all need to correspond exactly, and fitting the wrong mechanism can leave the door insecure or non-functional. If you are confident identifying these measurements and sourcing the correct part, it is physically possible. However, an incorrectly fitted mechanism can void door or home insurance coverage, and mistakes can leave the door unable to close securely. For most homeowners and tenants in Erith, calling a trained, insured technician is the lower-risk option, particularly when the door is already stuck or cannot be left unsecured overnight.
My patio sliding door will not lock properly — is this the same type of repair?
A sliding patio door uses a different mechanism to a hinged uPVC door, so a sliding door lock replacement is a distinct job from a standard gearbox swap. The sliding door system uses hook bolts and roller cams that engage with keeps embedded in the frame, all operated by a handle-mounted mechanism that runs along a strip inside the door slab. Faults here often also involve the keeps and strike plates in the frame, particularly if the door has dropped slightly in the track over time. We cover patio door faults across Erith and Belvedere regularly and carry common sliding door mechanisms in the van. Call us and describe the fault — we will advise on whether this is likely a one-visit repair.
I am locked out of my Belvedere home because the uPVC door mechanism has jammed — what should I do?
First, check whether any other entrance to the property is accessible — a back door or ground-floor window that is legitimately yours to use. If you have a spare key with a neighbour or a letting agent, that is the quickest resolution. If none of those options apply, call 020 3757 5599 and we will send a technician to you as an emergency lockout. We will verify your identity and connection to the property before carrying out any work, and we aim to reach addresses in the Erith and Belvedere area within approximately 30 minutes of your call, though we cannot guarantee an exact arrival time. We work damage-free wherever the mechanism and door condition allow, which protects both the door and any insurance claim that may follow if a fault rather than a lost key is the cause.
What is the difference between changing the euro cylinder and replacing the multipoint mechanism?
These are two separate components that happen to be fitted to the same door. The euro cylinder is the barrel that accepts the key — changing it means the old keys no longer work and new keys are issued, without touching the locking mechanism itself. This is the right course of action after a lost key, a change of tenancy, or if the cylinder shows signs of wear or lacks anti-snap protection. The multipoint mechanism — the gearbox, the locking strip, the hooks and rollers — is what physically moves the locking points into the frame when you lift the handle. If the mechanism has failed, changing the cylinder alone will not resolve the problem. In many cases both need attention at the same time, and we assess each component separately so you get an accurate picture of what is actually required.
Locked out or need a lock fixed? We are on the way.
Open 24 hours, 7 days a week · Insured, background-checked technicians · Up-front pricing
020 3757 5599