2004 Mercury Sable mirror

I already paid for this once but absolutely no response so I'll try one more time:

The electronic interior mirror in my 2004 Sable is loose and I can't figure out how to tighten it. I can pop off the square (actually it's trapezoidal) cover and I can pull the circuit board down, but I see no screws to be tightened or any other means to tighten the mirror so that it doesn't vibrate and wobble all over the place.

Simple question ~ how do I tighten it?

Simple answer?

Thanks