The motor on my driver's side was not working when I bought the car, however, I can just slide the support forward manually. The motor and support on the passenger side works just fine. Since I can slide it forward and backwards manually on the driver's side, I havent worried about it. I suspect that the previous owner left it out when he got out and when he got back in, forgot it was out and somehow broke it.
2006 550i Titanium Gray, Sports Package, Premium Package, Heated Seats, Navigation, Logic 7, Sirius, M-Tech Kit, PDC