Hoover HNF7148 goes out of balance no matter what size of load. ?

Hoover HNF7148 goes out of balance regardless of what size load or programme. Stops after banging very noisily before final rinse and spin. Tried all the usual checks, pump, drainage, filter, support springs to case, shock absorbers, level switch, belt and central drum bearing and nut,... I believe their is an out of balance sensor fitted? or is it the motor speed determines spin speed according to load? Could the motor brushes make the difference and if so are they about £25?