Drum turning slowly then stopping?

I have a white knight CL43 tumble dryer, the drum spins slowly then stops , I have changed the capacitor and the rear bearing , the belt seems to be under enough tension ,I have bypassed the thermostat on the fan outlet to see if that is the problem but to no avail , the next step is to change the motor , I was wondering if anyone had any advice of a way forward as it's expensive for a new motor !