dynalow, sounds like you have a stripped gear in the mechanism, a common problem. On Jim Forgione's great website he has a blip on it with a solution. There is a guy who makes metal replacement gears. I had the same problem as you years ago, bought a metal gear and it worked great until I sold the car. I love the shocked look on people's face when the arm is right next to their head.
Anziani
'97 CL600 58K