Bosch WVF2401 Washer dryer won’t spin full speed

[Max99]

I have above machine. In every respect it seems to work normally except that recently it will only very occasionally do the final spin at full speed (about 10{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of time might do a full speed spin). Usually does final spin at about 50{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of full speed, sometimes does not even make that. Makes no difference whether full or empty of clothes. So assume this rules out balance sensor probs? Machine seems go through full wash cycle fine (including all drum rotations) and drains fine. I have anyway checked pump and drain hoses clear (including hoses from bottom of drum to pump). No foreign objects in pump or filter. Pipe to pressure sensor switch is completely clear and I have also run machine with this pipe disconnected (i.e. simulates machine emptied) – still no full speed spin. Have gently blown into pipe to pressure sensor switch and it can clearly be heard clicking and also completely stops what low speed spinning there is if blown into while spinning. Assume this means the switch is working. I have changed the motor brushes. No change.

Some questions:
Where is the balance sensor (if any)? I can’t see one, or does it work by sensing variations in motor speed when mis-loaded?
How is the motor speed controlled? Is it an AC or DC motor (it has brushes so is presumably not an induction motor).
Would a duff timer cause it not to spin or is it more likely the motor control PCB gone duff? If I knew how it worked (how it controls speed of motor) maybe I could diagnose the problem more easily.

Thanks for any help forthcoming. Be as technical as you like – I am a one-time electronics engineer.

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