It seems to me that you might have a sticking window regulator. Take the door panel off and grease or WD-40 the regulator. That should do the trick. Those window motors never die,the regulators tend to stick quite often,especially in older MB's.
1987 mercedes 300E
1995 e320 conversion(hated the 300e grill)
Monochromatic Paint (Custom Blue)
Flat Badged (front)
custom "carbon fiber" console
18 inch HP EVO rims
Sold! Now I drive a Monte Carlo SS