The uPVC multipoint lock is a quietly brilliant piece of engineering — lift the handle and hooks, rollers and bolts engage along the full height of the door. But when it goes wrong, it goes wrong in a very particular way, and the single most expensive thing you can do is force it. This is one of the most common jobs our locksmiths attend, and the same story plays out weekly: a stiff handle forced one time too many, a snapped gearbox, and a repair that's now twice the price it needed to be.
First: stop forcing it
A multipoint mechanism that's getting stiffer is asking for help, not muscle. The gearbox at the centre of the mechanism is the part that converts your handle-lift into all that locking movement, and it is the part that shears when forced. A door with a working-but-misaligned mechanism is a quick adjustment; a door with a snapped gearbox is a parts replacement — and if it snaps while the door is shut and locked, it can become a lockout on top. If the handle is fighting you, treat that as the warning.
The 30-second diagnosis: open the door and try again
This one test tells you more than anything else. Open the door fully, then lift the handle and turn the key with the door standing open.
- Works perfectly open, fails when closed: the mechanism is fine — the door and frame are out of alignment, so the locking points are missing their keeps. This is an adjustment job, not a replacement.
- Fails even with the door open: the problem is inside the mechanism itself — usually the gearbox — and a part will need replacing.
- Handle feels floppy, loose or disconnected: the spindle or gearbox has already let go. Stop operating it, especially with the door shut.
If it's alignment: why doors "drop"
uPVC doors move. Hinges settle and loosen with years of use, and the material itself expands in hot weather — which is why some doors only misbehave in summer, or only on cold mornings. When the door drops even a few millimetres, the hooks and rollers start catching the edges of their keeps instead of sliding home, and the handle stiffens. The fix is realignment: adjusting the hinges (most modern uPVC hinges adjust in two or three directions), repositioning the keeps, and in more settled cases re-packing the glazing to square the door in its frame — what the trade calls toe-and-heeling. Confident DIYers can often improve things with hinge adjustments alone; the keeps and glazing are better left to someone who does it daily.
If it's the mechanism: the gearbox
Gearboxes rarely die without warning. The handle gets gradually stiffer, the lift starts to feel crunchy or gritty, the key needs a jiggle, or the handle stops springing back level. Any of those signs means the internals are wearing — and the good news is that failure doesn't mean a new door, or even a whole new mechanism. The gearbox is a replaceable unit, and in most cases a locksmith can match and swap it the same day, keeping the rest of the strip, the handles and often the cylinder you already have.
A note on lubricant
The classic oil-based maintenance spray is the wrong tool here: it attracts dust and grime that gum up the mechanism over time. Use a PTFE, silicone or graphite lock lubricant on the moving parts and locking points once or twice a year, and the mechanism will thank you for it.
What a repair involves and costs
A straightforward realignment is typically a single visit at the lower end of locksmith pricing; a gearbox replacement usually lands between £90 and £180 plus the part, depending on the mechanism — our price guide sets out fair ranges in detail. One genuine tip while the door is being worked on: if your cylinder is the original builder-grade fit, it is almost certainly snappable, and upgrading it during the same visit costs far less than a separate call-out. Our anti-snap guide explains the two-minute check. If your door won't lock at all tonight, treat it as urgent — an unlockable door is an unsecured home, and it's exactly the kind of job our locksmiths run out to same-day. Find your local LocksmithLocal here.
