In my 87 260E the two rear windows wont go down...for the most part. The windows do sometimes work, but the motor sounds horrible, and then once they are down they dont go back up. I am having trouble diagnosing the problem, are the window motors shot or is it another problem. I only bought the car with 82000 miles on it, so that should be a clue that it wasn't driven often, what do you guys think?