I'm assuming the window is off its track - it's resting on the bottom of the door. I've taken the interior door panel off and can see the window, even can push it up a little. Before I do anything drastic like take it to a shop, can I get it back on track myself? I can't figure out how to do it. Any help would be great.

'90 350 SDL - right rear window

 

I have the same problem in my 300SDL. It popped today while I was on the highway. I know its not the window motor, because I can hear it working when I try up or down with the button....?

Anythoughts anyone?

 

The same thing happens to me all the time - all four doors. I've become quite good at fixing this. I keep a window repair kit in the trunk and can repair this in less than 15 minutes.
As far as I can tell, it's a design issue. I didn't get my car until it had 200K miles on it, but I bet they were having problems with it as soon as it left the dealer bran new.
There are two things that typicaly go wrong, the plastic slider can wear out and break, that will require replacement, or the window just pops out of the track if the door is closed with the window open. The only thing that causes the window to pop out of the track is a poor design. There is no adjustment, it just moves to almost out of the track when lowered.
Incredibly frustrating. I have 300K miles on this car and it is in perfect condition with the exception of the stupid windows.

 

How do you go about fixing it, and what do you need?