My daughter asked me to change the Euro cylinder lock on her front uPVC door. Job looked simple enough but when arrived, I found that the fixing screw for the lock, which is usually a countersunk machine screw located in the side of the door, was in fact a grub screw that was only visible when the door handle was in the down (open) position. The multipoint locking mechanism is by Yale.
The thread to take the fixing screw in the lock is M5. I’ve found out that an M5 grub screw should take a 2.5mm Allen key, which I don’t have with me so I’ll have to go out and buy one. My big concern is that I unscrew the grub screw and it drops down inside the hollow uPVC because access and a clear view of the screw is very limited.
Has anybody worked with one of these fittings? How long is the grub screw and can it fall down into the innards? Is it likely to be screwed up tight against something or just into the length of the thread in the lock. I’m thinking I should maybe drill a small hole in the side of the lock housing so I can squirt some WD40 onto the thread. Any thoughts?