I've been called out a couple of times in the past week to metal doors which have the lock mechanisms inside the door. Now, I'm used to them having face plates which are removable giving access to the mech, however these doors only had holes where the hooks or bolts came out.
At one job the customer wanted new (screw in) cylinders. I figured I could drill a couple of small holes on the end of the door in line with the retaining grub screws. They said "no" and showed me a door which they insisted had had the cylinders changed. It did not have a hole in it apart from where the bolt came out, and you could no way reach the grub screws from there.
At another job (euro cylinder based) the customer was having difficulty retracting the bolt. The cam on the cylunder was ok, so I figured that the mech had worn. However, this door also had no hole other than where the hook came out. How do you remove the mechanism from the door ?
Is this some cynical ploy to get the whole door changed when the lock mech wears, or am I missing something really obvious ?