Just yesterday I was clearing my drains and I found one of the balls from the retraction mechanism in the drain tray (the one that attaches the arm to the triangular pivot). Apparently it had worked loose over time. I put it back in and lubed and reattached the arm. I didn't notice any strain or slowness, but it's worth checking.
As far as the headliner: Cut it out. They only added it in 2001 (or so), before that you could just see the frame. I'm not sure why Porsche added the headliner; the frame isn't ugly.
(Pic borrowed from Rennlist.)
Threaded Mode
