The outer (painted) housing around the passengers side mirror has come away from the window/door after getting bumped. It is still on the car but it is loose and water can get behind it if it rains. How do you go about re-attaching it? Pushing it back doesn't fix the problem, it just comes loose again. Do you have to take the inner door panel off to get to it or is there a simpler way?

Any help or suggestions (Non sarcastic I hope) are appreciated.

Steve