This is a classic case of a failed capacitor. You will find the faulty part bolted/screwed to the side of the motor. It will probably be showing signs of overheating.
Remove the wiring lead and take the unit off the motor and see if you can identify its rating (about 8Uf) and Google it along with the make & model.
Failing that, go to www.espares.co.uk and follow the spares links for your make and model.
Expect to pay £10-£17.
Also try www.spares4appliances.co.uk
Geoff in Wales
October 2012