We have been experiencing some problems with the door lock. For some reason the whole mechanism is loose and slides up/down and fore/aft. I have removed it and tightened all screws but still has a lot of play. Keypad code doesn't always work and must use key. Batteries have been replaced, treated with silicone dry lube. Still is iffy. Is the looseness the cause of the problem? Would washers or shims keep it from moving? Any suggestions? Advice is appreciated.