I've got a 1989 300E (W124) and had a bracket break in the sunroof mechanism early this year. Bracket is part of the tilt-up-in-back feature (when you need ventilation but not sunshine or rain) and is known to go bad. DON'T TRY TO FORCE THIS OPEN, you're likely going to make things worse...
MB revised the design and the replacements are stronger. Cost to replace (parts and labor) was round $500 at my local (very trustworthy) independent.

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Jay Yambrovich
Scotts Valley, CA.

1993 300 CE Cabriolet (A124) 131K miles
1997 C-280 133K miles

2000 BMW R1100RT 69K miles
1989 300 E 216K miles (sold)