Sticky multipoint door lock.

[Richard Worrall]

The locking latch on my upvc door is sticky when unlocking as though something is catching inside the gearbox. I've taken the gearbox and bits off the door and determined it's definitely the gearbox at fault as the barrel lock turns fine. I'm not sure which replacement to buy as it's all attached to the door sliding lock part and won't come apart as far as I can see. It's got Fuhr 36 stamped on it and the measurements are: 35mm backseat, 90mm PZ, 53mm total depth and 185mm top to bottom. Pics hopefully attached.
Thanks

 

[ronniecabers]

Suspect looking at those pictures that the gearbox doesn't come off, as I can't see any retaining screws.
If it's a 4 ' roller cam ' with deadbolt , look up a fuhr 856 , that's the closest from memory

 

[Richard Worrall]

Correct can't see a way of detaching it and yes it's got 4 rollers on it. Thanks for that info I'll have a look

 

[Richard Worrall]

https://www.lockshopdirect.co.uk/products/fuhr-856-type-1-latch-deadbolt-4-rollers-28433/#variations

Does this seem correct?

 

[ronniecabers]

To be honest, if the measurements all seem to tally within a few mm ( lock gearbox is the main bit ) then you should be fine. The roller cam keeps on the door frame should be able to be moved to suit .You may need a little fettling of the frame as it's an upgraded lock to your original , which I believe is discontinued