It looks as if you MIGHT be able to access the folding hinge mechanism without taking the mirror off the car. The mirror glass is a separate replaceable item and can be removed and reinstalled. There are some tricks to getting it out and reinstalling the glass, so if you can lay your hands on a FSM it would be useful. The FSM doesn't seem to address how to deal with a loose hinge, but their picture of the glass removal shows what looks to be a nut at the hinge location. I don't know if I can scan and post the picture tonight, but it might be online somewhere.