I am having an operational problem with the Thermador downdraft unit. The unit was locked in the up position and I thought an easy fix would be to replace the switch, so I did, and it didn't fix the problem. I then moved the fan out of the way and checked the gear motor and it showed continuity. I then discovered that if I moved the cam (attached to the gear motor shaft) slightly off vertical that the unit worked fine. The exact same thing happened in the down position and required the cam/shaft to be moved an inch or so off vertical and then it worked again. It's weird, the unit works great so long as the cam and arm are not in a vertical position. Any ideas? Thanks for your input.