how to mount the interior MB mirror, 1987 SDL
 

I have a good new mirror but I don't know how to demount the old one. Can someone tell me this secret? I can see a certain mechanism with a spring on the new one. Martin

its pretty simple...just pull it down and out.

The blasted things requires more force than we would thing reasonable. Yank like heck from one side to remove. Insert one side, have helper hold in place and pound with rubber hammer (actually, use something like a 2x2 up against the base of the mirror and hit the wood with the rubber hammer).

Grab hold and yank downward, forward and kinda off to one side as you do. Once you have it out you will see how there are pins that are spring loaded on each side. It should pop in with a little force.