Hotpoint ‘juddering’

Hotpoint 95622

Yes, I know this is ancient, but it works, sort of.

On wash cycles it has recently started ‘juddering’ around, i.e., there will be a buzzing sound when the drum should rotate and the drum will then start stuttering around at half-speed for one or two revolutions. It will then suddenly take off and rotate at normal speed for a few revolutions before pausing, as normal. After a few seconds it will start juddering around in the other direction.

The juddering is accompanied by sparking around the motor brushes. I assumed that it would be the brushes or commutator, but both brushes have plenty of life left in them. Blowing out the motor with a compressed air aerosol seemed to cause it to operate normally but then it reverted to the juddering mode of operation.

Any ideas what might cause this? Is it wear of the commutator and is it repairable?

Thanks for any assistance offered.