How to track down fault with my Arisotn WD12UK Washer Drier?

My Washer Drier has started to act up..

In the middle of a wash cycle the program selector switch has started to to track round the dial continuously and the washing program stops.

I have replaced the Program Selector module but that has made no difference.

So question in two parts..

1. What other part could be faulty that would make it do this?

2. Would it be repairable by some one with very limited knowledge of washer driers or is it time to bite the bullet and buy a new one...?