The ball on my VC rearview mirror was loose. I took it off, set it upside down on the counter, packed it with Elmer's Wood Glue, wiped off excess, and let it dry overnight. Voila! Tight ball. Any other easy solutions out there?

 

It probably won't last very long. wood glue is only good on raw wood.

 

Sounds like a reasonable solution since it's inside the car. You just needed a little extra "filler" in the space that keeps the ball tight. I've used a drop of super glue on exterior mirrors that were floppy and never had an issue again. Lots easier that smacking it with a hammer and punch or something that could damage the piece ) And hey, if it doesn't last long, just do it again. Or choose another glue!

 

I'd be interested to know how long it holds up as I have a vehicle with a loose mirror.