Originally Posted by MAVA

My Approach is not to remove the headliner.

It is hard to arm chair it from here. In the case of two of my cars, it had foreign matter that came in on my S-Class, and my 2002 E320 the spring arm broke that moves the wind turbulator up as the sunroof opened. I think that what broke one yours because on the W210's I find at the junk yard these are broken half the time. Here is a process how to remove the sunroof the W140 S-Class which is very similar on the W210.

DIY - W140 Sun Roof Resotoration / Repair / Service / Dismantle (ALL PICS) - Mercedes-Benz Forum

Take a peek and see what you find. You could have a "Fall Squirrel" in there?

Best of luck,

Martin