My mirror was really loose. If yours is also, super glue probably won't fix it.
I had a loose passenger mirror. I had to break the glass out, luckily it was all scratched anyways. Once the glass was out, I found that the swedging on one of the retaining posts that hold the mirror retaining plate tight to the pivot ball had broken off, so the retaining plate was only being held on one side. I had to drill the post and install a small screw into it. Once I tightened the screw, the plate was held tight to the pivot ball, and the mirror is nice and tight again. I had a glass shop cut me a new piece of mirror (only charged $25), and the mirror is fixed, ready to be painted. Once the mirror gets painted with the car, I will glue the glass back in. If you want to see some pics, send me an email to chuck.vedra@yahoo.com, as I can't seem to get pics to load up on the site.

Chuck