I put this up on the 2doorpost forum - thought it might be of interest here too...

I thought I'd share this since I know mirrors that won't hold their position are a common problem. I used a spare mirror that didn't matter if I wrecked it. I figured the mirror glass had to be held in place by some sort of adhesive so I put the mirror face down in a suitable sized coffee can and filled it with gasoline to just above the ball socket. I let it sit for 24 hours and the glass came out with little effort. What I found inside is in the first 2 pictures. The glass is secured by black silicone on 4 pads. The tension for the ball pivot is provided by the metal plate you can see. On this one the plate had separated from one of it's mounts. The design here is the mount post was mushroomed over the plate to hold it tightly in place (kind of like a rivet). To fix it I very carefully drilled out the post to accept small sheet metal screws. Be extremely careful here because if you drill too far you'll come right out the back. Also you don't want to get too close to bottom because the heat of the drill will discolor the chrome. The last 2 pictures are of the repair finished and the mirror is as tight as the day it was made.