Originally Posted by Texasgeezer

On my 95 E300D my window problems have primarily been related to the module beneath the rear seat. Those small relays have very small contact points. I've been very careful to clean them due to the small size. I did order about 20 of the small relays, but have been fearful of replacing them due to fear of not soldering them in correctly.

Plus I've been able to source a few spare modules.

I believe there is a larger relay near the master cylinder that I replaced since it provides power to the rear seat module.

In troubleshooting window motors I use a battery charger to provide a higher voltage if the window motor doesn't move with battery voltage.

If that doesn't work I take the motor out and take it to a nearby repair shop to see if it can be repaired. We're lucky to have small shop nearby that is family owned & they have years of experience.

And the fuses should be replaced with copper contact ones to get better voltage transfer and current flow.