My 87 560SEL right side passenger window quit working months ago. Worked one day and not the next. Purchased a new switch. Nothing. Today I tested the power at the switch, all ok. Took off the door panal, power to the motor. Pushed, pulled, prodded. Window still would not work. Before putting the panal back on I went to the last resort. Took the ball-peen hammer and gave the motor a nice blow. Turned on the key, pushed the window button and the window lowered about half way then bound up. Raised it and lowered it twice and then it seemed to get back in allignment. Window works well, just slightly slower than the other three. I believe the door got slammed or at least shut too hard. The motor/regulator was misalligned and caused something to bind up? I know you are not supposed to repair MB's with a hammer, but at least I did use a ball-peen instead of a sledge or carpenter hammer. I also know that I will be working on this window again.