Sorry, I know this isn't an answer!
I have what sounds like the same problem on the FL828.
The motor on mine has no brushes; it looks like an A/C induction motor to me as there are outer stater coils. There are no screws to remove the outer motor casing (fixed with steel locking tabs). Mentioned in this forum elsewhere is something called a 'tacho magnet' - well I can't find anything that goes anywhere near the rotor from the outer casing, all the wires go into the stator windings.
I've changed the belt but although the new belt is a lot tighter the motor still 'stalls' when the load is heavy (rinsing and spinning). The belt (old and new) doesn't slip but when the load in the drum is at the 11 o'clock position the motor appears to lose its torque and stall. If you supply manual assistance it rotates. This happens in both clock and anti clockwise rotation. There is a suspicious smell of 'electrical overheating' (hot phenol /epoxy)
I do not understand how the feedback loop works - if the belt slips you'd not want the motor to keep spinning otherwise it could start a fire. similarly, if the drum got jammed somehow you'd want the control system to reduce/cut the motors torque otherwise it would overheat?
Have you solved your problem ? If so I'd be grateful for a few pointers.
Cheers, Jon
Jonathan Leak, February 2006