Correct me if wrong ( and I'm sure someone will ) but there are probably two reasons your roof is not working. And I think both are hard fixes:
One, you have broken the cable to roof. I believe this runs thru headliner and into trunk are .
Or two, you might have a motor which has stripped gears or cable attachment issues ( not sure on this as I have not worked on early MB sunroofs ). Might check my sources and repost later if I can find something out !