I just did this job on my '87 420SEL, but I didn't have the problems that you're having. The problem may be that, when something is jammed so the window motor can't go through its entire range of motion, it exerts a lot of force on the lifting arm and on the motor's three mounting points, and this can bend the lifter arm or said mounting points. It sounds like the lifter arm is bent or cocked so it is not lifting straight up and is instead trying to shove the window out of its channel. Also, if the window can jump out of its channel, there must either be something in the channel itself that it causing the window to jump out, or the channel may be set too loose, or the channel might be broken or defective. You can adjust the channels by loosening their mounting bolts and sliding them toward the window. Check the lifter arm and the interior door sheet metal, where the motor mounts, to make sure nothing is bent. You might need to compare the lifter arm with the one from the other door to see if it is bent.