After taking a mirror apart for paint touch up, I see now what the problem probably is. These mirrors are made up of a bunch of different parts, rather than a solid shell and the mirror and motor assembly.
Every time you split something you create potential for movement between them.
The door mount isn't secured to the mirror frame across the entire width, but just close to the mount. The shell is 4 parts, instead of 1 or 2. In fact, the little black part at the bottom edge is held on by nothing more than the painted part overlapping it with a tiny lip. Just no structural integrity.
The problem with my theory is the fact that a lot of us don;t have this problem.
A question for the owners with the vibration: When you move the glass manually, does it ratchet (rapid clicking) in all 4 directions?