Well the other day I got the dreaded tilt but won't slide issue with my sunroof. After doing a bit of research and head scratching I found an easy fix.
Part of the mechanism consists of a small wheel that sits in a slot in the runners. There is a little rubber that sits on the end, and it would appear that over time, this loses its thickness, so when that part is pushed back, instead of the wheel riding up and over the groove, it pushed downwards, and stops the mechanism from moving back. Research would show that this usually happens on the passenger side, and was the case for me.
One way to fix it, I guess, would be to find a rubber oring that is thick enough to make the resting position of the wheel a tiny bit higher. I didn't have any o-rings, but I did have some od 4.8,, id 3.0mm plastic pipe that is the perfect size to fit on the metal part and lift it up enough that it works every time.
Tilt your sun roof, then gently tap back the fabric cover, lower it and push it back out of the way. Now - CAREFULLY try sliding your mech back. See if the wheel digs in. Now try a fingernail under the rear of the wheel and try again. It should lift up correctly this time. I took off the rubber bit, and cut a short piece of my plastic tubing, slipped it on and it works like a charm. Slide back the fabric cover and gently press back into place. Pics below - any questions, just ask.
The piece I cut was about 5mm or so long. I do have about 1.5 meters of the pipe left, so if people need some I'm happy to post these out (just cover postage).
Now - a grease question. I have some Klüber Klübersynth UH1 64-2403 silicone based grease specs:
DIN EN 377 Class D
Full data sheet here http://roghankar.com/new/statics/upload/attachments/product_731_Kluebersynth_UH1_64_2403.pdf
Any good for the sunroof, or should I just buy this from the bay I can get the Klübersynth foc
Driver's side showing the little rubber end
Passenger side with modification