I removed the rearview on my 140 and my 129 because they both were broken, it is a very tricky process. The mirror actually snaps in there, it uses a spring with two caps on the end that when it passes through the mount locks it into place. This is where the mirror goes into the upper cowl between the widshield and the roof. you literally have to "pop' it out to remove the mirror. The mirror doesn't bolt in, just the parts around it are held on with screws. The mirror in my 96 129 was just loose, but the mirror in my 92 140 was broken. I wish I had a pic, Good luck!
Brian