Gearbox and Multipoint Mechanism Replacement
The gearbox is the heart of any uPVC or composite door’s multipoint locking system. It is the component that translates the movement of the handle and key into the simultaneous engagement of all the door’s locking points — hooks, rollers, deadbolts, and shoot bolts — into their keeps in the frame. When the gearbox wears out or fails, the door may refuse to lock, become impossible to open, or lose the ability to engage some or all of its locking points. Gearbox failure is one of the most common lock problems in British housing, affecting a very high proportion of uPVC doors installed in the 1990s and 2000s that are now reaching the end of the mechanism’s service life.
Signs That Your Gearbox Needs Replacing
Gearbox failure is usually gradual rather than sudden, though sudden failure can occur. Watch for these signs:
- Handle has become stiff — The handle requires significant force to lift or lower. Early signs of gearbox wear.
- Handle has dropped — The handle no longer sits horizontally at rest but droops downward. The spring within the gearbox has weakened or broken.
- Grinding or clicking when operating — Internal gearbox components are failing. The mechanism may continue to function for a period but is close to failure.
- Door locks but some points do not engage — One or more hooks or bolts are not extending into the frame. The gearbox is no longer driving all locking points fully.
- Door will not lock at all — Key turns but nothing engages. Complete gearbox failure.
- Door locked, will not open — Key turns (or was turned) but locking points will not retract. This is an emergency situation — the gearbox has seized in the locked position.
Gearbox Locked in Position — Emergency Entry
A door locked with a failed gearbox that will not open is one of the more challenging locksmith situations. The cylinder may operate correctly, but if the gearbox is seized the door cannot be opened in the usual way. Our engineers have specific techniques for freeing seized gearboxes and for gaining emergency entry through other means when necessary. This is an emergency situation — call us immediately on 0330 341 4041 and we will be with you within 20 minutes.
Gearbox Brands and Compatibility
UK uPVC and composite doors use gearboxes made by a relatively small number of manufacturers, though the specific model fitted varies enormously between door brands, installation dates, and door dimensions. The most common brands we encounter are:
- Maco — Very widely fitted, particularly on doors installed in the early 2000s
- Winkhaus — Common on higher-specification uPVC and composite doors
- Roto — German-made mechanism found on many quality installations
- ERA — Widely used UK brand, including the Fortress and Safeguard ranges
- Yale — Common on own-brand door installations and as supplied with Yale-branded door sets
- Avocet — Frequently fitted on composite doors
- Fullex — Less common but still encountered on doors from the 1990s-early 2000s
Our engineers carry the most commonly required gearbox models in stock and can usually complete a replacement at a single visit. For less common mechanisms, we will advise on lead time and can provide temporary securing of the property while the replacement is sourced.
Measuring for a Replacement Gearbox
Gearboxes are not universal — the correct replacement must match the original in several key dimensions: the handed orientation (left or right), the backset (distance from the centre of the cylinder to the edge of the door), the case height, and the distance between locking points. Our engineers take these measurements on arrival and match them to the correct replacement. If you are unsure whether a gearbox can be sourced for your door, call us and our dispatch team can advise based on the door make and approximate installation date.
The Full Mechanism Strip — Hook and Roller Replacement
In some cases, the gearbox itself is functioning correctly but individual locking points — hooks, rollers, or shoot bolts — have worn or broken. These can sometimes be replaced individually without replacing the entire mechanism strip. Our engineers assess each case and advise on the most cost-effective repair approach.
Adjustment Before Replacement
Before recommending a gearbox or mechanism replacement, our engineers always assess whether the problem might be caused by door misalignment — a very common issue that mimics gearbox failure. If the door has dropped on its hinges, or if the frame has moved, the locking points may be failing to enter their keeps due to misalignment rather than mechanism failure. A hinge adjustment or keep repositioning can resolve this without any parts cost. We always check alignment before advising parts replacement.
Pricing
Gearbox replacement starts from £120 including a new gearbox and all fixings. Full mechanism strip replacement (where more than the gearbox needs replacing) starts from £160. Prices given upfront at diagnosis; no call-out fee. Same-day service available in the majority of cases. Call 0330 341 4041 to book.
