the little plastic pieces that hold it to the frame. its rattles all over the place and basically hangs by the cord.
I bought a new/used one on ebay that is perfect same color and everything. I paid $495 which cheap compared to the dealer who wants $700-900. I got it from a seller called fivestar007.
It takes a pretty good push. But push on the right parts.
My mirror is mounted on a metal ball. The bracket holding the mirror has a ball socket that pops into place over the ball. The socket is basically a bunch of plastic fingers with a thick metal spring that goes around the tips of the fingers and makes them clamp down on the ball. When you press the socket onto the ball, you have to spread the fingers against this spring. It's a pretty stiff spring.
I don't know the screw that you are talking about. It was a long time ago that I fixed my mirror. But, I don't recall any small screws holding the mirror together. There may have been screws holding the garage door opener in place inside the housing, or maybe it just clipped in place. I don't remember now. I wish I had taken pictures. Just make sure you pull on the strong parts when removing and replacing the mirror on the ball.