Ok, I've searched, but can't find any info on tightening the rear-view mirror. every time I hit a bump, it drops down to a different angle and I can't see behind me. Visibility is poor to begin with and this makes it dangerous to have to keep adjusting the mirror. I've looked and can't see any type of screws in the mirror hardware. '92 convertible.

Thanks!

Hello, I have a 93' and it did the same thing. So... I took the screw out that held it to the swivel post and inserted a thin washer in the attachment point. Re inserted the screw and tightened it up. Seemed to work for me. 

Looks like they didn’t leave any room for adjustments other than the day/night mirror. With all those wires it doesn’t make it any simpler to just replace the unit.

I had the same issue with my 1991 and I placed a small drop or thread lock fluid on the screw and reinserted it and made it tight.    I have had no issues for quite some time.  Only use the general thread lock fluid, I believe the permatex brand is blue in color.