We have the same machine and the same problem. Additionally, the machine smells horribly. We have investigated the problem a little bit. The smell comes from the main motor. We have fitted new brushes and resurfaced the commutator. The machine worked fine after that using only 400rpm spinning. However, trying 1,000 rpm - same problem came back.
It seems that the commutator cracks and two of the poles start lifting and causing the brushes to lift and fire.
So - new motor seems the solution.
However, it would be nice to know what problem F11 means and also whether this is a design fault, manufacturing fault or materials fault. After all, the motor must be spinning at about 30,000rpm. This is quite a lot for such a machine.
DD, June 2007
