If you’ve ever experienced your rear view mirror sagging or simply rotating downwards on its own, it’s likely due to the mirror socket no longer holding the ball mount in place. Most of the time, there are these plastic teeth that hold the ball joint in place and when these plastic teeth break off, there is no longer enough force holding the ball joint securely. As a result, the rear view mirror starts to sag and slowly move down on its own. This can be an annoyance as you constantly have to put the mirror back up, only to have it rotate down again and again.