Side view mirror mounting is loose help

Drivers side view mirror. 2 screws hold it to the door. Appears that the screws just screw into the sheet metal of the door, thats it. One hole has become enlarged and so the screw just spins. Any tricks for getting this to tighten up? I tried wrapping the screws in Teflon....fail.
Thought about maybe pushing some plastic anchors into the holes, then screw it in? Any ideas? 66 dart sedan 270
Author: admin