Arrgh! It's cold & rainy & dark, & the drivers side power window on my 83 300D will not go up. It is only down an inch & a half, but will not roll all the way shut. It will not go any further down, either - which is good, and it seems as if the power mechanism has just ceased operation altogether on that window. The other windows all work.
I assume its a vacuum thing, and that likely means that I am going to have to take the door panel off to poke around to find what went wrong. As my door panels are in very nice shape I want to be careful to remove them without damage & so they will go back on easily. I will need a special tool, I assume. Tomorrow when it's light out I will check fuses, and look to see if it is anything obvious. However, I hope to draw upon the expertise of this group for suggestions as to probable causes and the tools needed to remove the door panel and repair this window.

Any suggestions or advice would be gratefully appreciated. This would be a small problem for some of you, but it is a new mechanical problem for me. (I have always owned vehicles with manually operated windows in the past)

I don't know which car you are referring to but the door panel comes off different on the W123 versus the W124. Anyway, before you start taking anything apart check to see if the passenger side rear window works. If it does not then it is in the electrical system/fuse. The drivers door and the passengers rear door are fed from the same fuse. If the pass. door window works then they are getting power.
The next thing you want to check is the switches. Remove, clean and regrease the little ball in them. Be particular when you bet the switch out and pry it apart because that little ball will go rolling never to be found again - I have experienced this. If there is a bunch of crud in there this could be your problem. Once the switch is clean and back in place and you continue to have window problems then it is time to get inside the door panel.
Remove it and once you get it off you will see a plastic film covering the door. Slowly, start in the corner and peel it back until you can get your hands up in the hole to access the regulator/motor assy. Try not to tear the plastic because you will want to put it back on when you are finished. You will not have to take it all the way off. You should be able to pull the window regulator/motor out and hopefully you can bench test it to see where the problem is.
If you just want to shut the window try having someone mash the "up" switch and with your hands on both sides of the window see if you can pull it up.

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Jim