There's nothing quite like cruising around in your Mercedes-Benz C-Class with the sunroof open, until it starts to rain. You hit the switch to close the sunroof, and nothing happens. You're not doomed to suffer raindrops falling on your head; instead you can close the sunroof manually.
Remove the lens on the overhead light by prying it off with a screwdriver.
Slide the locking tabs towards the windshield and pull down on the housing to remove the inside of the roof light assembly. Leave the wiring connected.
Insert the S shaped Allen wrench supplied with the vehicle into the left side motor hole.
Turn the crank clockwise to close the sunroof.
