Loose Rear View Mirror - 2011 Prius w/ Sunroof

I know that there have been similar threads on the site, but I haven't seen one that specifically addresses a loose rear view mirror on a Prius (this is a 2011, trim III with the sunroof option) with the sunroof/solar panel option (since the ceiling is different I'm wondering if the mirror assembly is different, as well). The rear view is loose, but the problem seems to be in the base of the mirror where it attaches to the windshield, not the pivot assembly of the mirror itself. I've seen in some of the other threads reference to a torx screw that can be tightened to eliminate the movement, but mine doesn't have any set screws visible. There seems to be a cover which I suspect slides off of the windshield attachment, probably held in place with a tab/clip. I don't want to start trying to remove anything without having some idea of what I'm doing and wanted to see if anyone has had the same experience. I'd appreciate any help as I'd like to fix the problem myself instead of taking the car to the dealer. Thanks!

 

Bump.