Rusty at BuyMBParts sells a 2 oz tin, or you can buy the lifetime supply for $50 and lube every MB for miles around.

I'd guess you are either getting stuck on the wind deflector of the rails are REALLY dirty -- the clutch in the motor slips at the full open and full tilt positions, so the motor running without the roof panel moving means its to sticky to slide or is jammed.

Take a look and the lift angles on the sides, too -- if one is broken, chunks can jam the roof.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!