So i just bought an 01 S80 yesterday As Is. Everything looks pretty good and after i left i tried the sunroof. It opens fine but it wont close properly. I have to keep tapping the button and checking out side to make sure its sealed. Does anyone have any ides how to fix this?

 

My GF's 2002 has the same issues. For a quick fix, make sure the metal guides are seated in the rails. I used needle nose pliers and seemed to work. Hope it helps.

 

Sounds like a lubrication issue here, too.