Window Regulaator; drivers side
 

It now appears that the window regulator is shot.

Where exactly is the window regulator for the drivers side window? I understand that it is somewhere inside the door, but before I go ripping my door apart, I will research thru the talent and experience that you gentlemen offer. That has proven wise in the past, as some of you have provided tips in the past that my Haynes manual did not alert me to.
I also understand that it is possible to "hotwire" this window motor so the window will go all the way back up. Has anyone heard of this procedure?
Regards

what exactly is the window doing??? sometimes, with these regulators the slides simply go bad. I lucked out and on both my rear windows on my 300SD, it was only my slides that were bad. I got quoted 200$ to fix from a shop and in about an hour and 12 bucks later i'd fixed it myself. I"m pretty sure your car has the lifting arm style and not the cable drivin ones. I'm sure someone on here can give you an idea of how to get that door apart, i can have mine on my 300SD off and back on again in 5 minutes flat, but the W123 may be differant. Hope this helps,
Ryan

W123 is straight forward. Remove the door panel - take off arm rest, remove black plastic cover behind inside door opening latch and remove that phillips head screw then pry the bottom of the door straight out. Also remove the door lock push/pull knob. When all that is free push up on the panel. Next you will come to the vapor barrier (plastic cover between the panel and door). Start peeling it away at one of the corners. Take your time here because you will reuse it and don't want to rip it. Once that is out of the way you should be able to look around inside the door and see the regulator and inspect the slide.
On my 300D the "teeth" are shot in the area where the window is closed. I will eventually get around to replacing them. They work but just make noise when they get all the way shut.