Zanussi TCE7227 Condensing Tumble Dryer - Intermittent fault?

The dryer starts but suddenly stops again. I have replaced the motor capacitor on a previous occasion and this has checked out OK this time. There is an additional motor starting capacitor which checks out OK and the relay to switch this in operates.
The problem is with intermittent loss of electrical supply to the motor as tested with test meter (the supply comes from the control/pcb board). I have tried the dryer on cold drying and on fixed timer drying (to by-pass the sensor in case this was causing the problem) but still have the same fault. The only other point is that the dryer runs longer (about a minute)when cold before stopping, but runs less than this if it is immediately reset and switched on again.
On the PCB there are 3 relays, one of which I believe controls motor direction only and the others I suspect are for the heaters. (The heaters do appear to work by the way). These relays are all OK.
It appears there is a fault on the PCB but I would like this to be confirmed before forking out for a replacement. I have also heard about these PCB having to be "reset" using a push button combination.
Grateful for any help