Hello together, despite the search I found unfortunately no solution for my problem. It is about an E-window lifter. The driver side window lifter front was defective (broken teeth). The replacement has impeccable teeth, is nicely greased and works perfectly in the developed condition (completely up and down). I then installed the new window lifter: a) Right lifter screwed to the right rail b) Left lifter inserted into the left rail; directly left at the Kan t the white “plastic part” (so that the window does not stand crooked and has straight running?) used c) Both remaining arms screwed (left or left at the top of the window lifter) d) window lifter itself 3x screwed however The problem is the following: The window goes down from the very top (too) about a hand width and vice versa. However, more does not work. You also notice quite clearly that with each piece down (window on) the engine has less power. I also noticed that The left guide tries to turn itself. If the window goes up again, everything is okay again. You don’t see or feel it hooks somewhere. Fortunately, I don’t have the usual “defect” on rails or the like. Somewhere the worm seems to be, especially the addressed white plastic part which sits on the left of the left arm in the rail. Maybe it doesn’t belong there at all? Would be great if someone could help. lg