Just a note regarding some electrical problems I encountered.

I bought a 1990 300E with small issues. Most of which were electrical in nature.
Sunroof would work intermediately, windows the same.
They would work only for a moment after start up, then nothing. Turn off the car and again the windows and sunroof would work on start up, then nothing.
Then the next day one window would work, the others nothing at all.

It was all perplexing.

Checked out all of the fuses and they were all intact, but they were old and appeared to be the original fuses.
I twisted and turned the fuses around in their respective holders. Some I removed and cleaned them up a little. I figured that would kind of improve the conductivity.

Still had the same issues.

Finally, I changed all of the fuses out, with new ones regardless of how they looked and voila. Everything works as it should.

I'm just pointing out on some of these older cars, it's just the simplest of matters to get things working as they should.