I was having the same issue with mirrors flopping around before eventually catching, but just recently fixed with the gruven parts mentioned earlier, and it works perfectly now. Turns out the plastic gear that mates to the motor only had minor wear, but the indexing rings on both mirrors were broken into multiple pieces.
The replacement gear is brass and the new indexing ring provided with it seems more durable than the OEM.
The fix wasn’t difficult, but care must be taken when cutting open the motor housing (it’s sealed, so a dremel must be used) to avoid damaging other internals. As long as you take your time and use a feeler gauge to check cut depth you should be fine.
I wanted to post because it seems some people worry about mixed success with this. I was only able to find one YouTuber documenting the fix and he made some mistakes along the way, hence his mixed review.