Bosch 4030GB/04 won't turn?

Had this machine for years. Water pumps in & drains out but drum won't turn. Drum will turn by hand. Done some digging and concensus is its proably the motor or the brushes. Would like to do this myself..but can I undo the Bl**dy nuts...No.

Does anyone know if the retaining parts undo in some strange way?

Any other idea on what might cause the fault are gratefully appreciated.

Raoul