tighten out side mirror

Is it chrome twin post mirror? If so, it might be hard to get the mirror glass out without busting it. If there is any space at all between the edge of the mirror glass and the housing, you can soak it in lacquer thinner for a few days to loosen up the adhesive holding the glass to the mirror body. Once you get the glass out, you can then figure out how to tighten it up. The thin plate that rubs the ball to hold tension will either be held down by screws, or will have solder joints. I've never had one of those apart, so I don't know which it is. I've never had much luck resoldering the plate, but I have drilled the spots with a tiny drill bit and installed screws with washers to hold the tension plate tight.