Thread: Wing mirror won't hold adjustment.

I have a 1994 Defender 110 in good running order.
The passenger side rear-vision mirror won't hold adjustment, however hard I tighten the hex-head engineer's screw under the base of the mirror.
Is there a solution to this problem, such as using a shorter screw?
Any advice much appreciated.
TAK247.

FWIW, When confronted with this problem I have used a 1" squ. piece of rubber waffle pad as a washer & clamp up to that. Maybe this will work on yours?