Two questions. Do you need a complete drive or just the laser? I found a laser by googling BMW MK3 laser repair. Optical Laser pickup for BMW MK3 Navi CDM-M2 Mechanism

Didi's pictorial instructions on this forum for the MK4 laser repair lists many places to buy drives and lasers. Review them. One of them that I looked at had drives also. I think one was Gerner. The complete drives were not cheap but might be worth a search. Your drive is probably a CDM-M2. One of my old MK3s also has the VDO number 22SY591/23B.

http://www.xoutpost.com/electronics/...-nav-unit.html