One or more door windows may stop working due to a failed window regulator. Replacement of the failed regulator will be necessary to correct this concern.Google+
Car Problem Reports
Mercedes-Benz 560SEL Window Regulator Failure is Common
Mercedes-Benz 560SEL Problem
Average Mileage: 243,210 mi (225,000 mi - 261,420 mi)
Visitor, 1990 Mercedes-Benz 560SEL, 225,000 mi
Right rear window quit working correctly. I could hear motor spinning, but window would not close. I found that the plastic slider on the window regulator had self destructed. Since I had already purchased a new regulator, I went ahead and installed it. I subsequently found out that you can now get the vinyl slider and just replace that part.
Visitor, 1991 Mercedes-Benz 560SEL, 261,420 mi
2 of the button are stuck and i switched the button out with one i had it still didn't work.