Fuhr Replacement uPVC Gear Box Door Lock Centre Case 30mm Backset GenuineFuhr Multipoint Lock Gearbox 30mm A replacement centre case gearbox for the Fuhr multipoint door lock mechanism. If you're having problems with your door lock, the gearbox is almost always the problem and replacing it with a Fuhr Multipoint Lock is as simple as removing a few screws. Fuhr Multipoint Gearbox Centre Lock Information Important measurements: 30mm Backset 92mm PZ Centres This is the mechanism inside the door that is operated by the handle.