in my 190 I did this-
1) lower the window half-way, undo the retaining screws securing the window.
2) undo 2-3 screws near the front of the door securing the regulator. there may be more screws
3) remove the regulator through an opening in the door.
Oh, unplug the motor wires-motor is attached to the regulator.
4) swap the motor to a new regulator. I don't see how you could repair the teeth,
5) install the whole shebang back where it belongs
Took me about 1 hour. The trick is to find the screws securing the regulator through the door panel
1985 190D 2.2l Sold-to Brother-in-law
1996 Mustang 3.8l -"thinks it's a sports car"
1988 Grand Wagoneer - Sold (good home)
1995 Grand Cherokee Ltd -"What was I thinking??!!"