How can I fix my Hotpoint wasing machine?

My Hotpoint WMTL80 top loader washing macine continuously rotates the programme control switch, but after replacing the switch the same fault exists. How do I find info on the main processor electroic pcb that drives it?
How do I repair it please? A new board costs £80, so how do I confirm that it is the PCB thats faulty, any suggestions please?
I've taken it all apart, cleaned contacts and checked for dry solder joints etc.

Thanks for any help.