hi how can i fix my diplomat apl 8215/1 integrated dishwasher?

hi my dishwasher worked fine then one day switched on as normal with rotary dial, fills ok, element works, timer dial clicks around through its cycle but wont pump water around to wash plates. if you turn timer dial around it will drain at right time just wont pump water around. i ve had door cover off to look for any obvious signs of wear but none obvious, no smells of burning on any components, ive exchanged the mini pc board with 3 lights on from a relatives identical m/c but no joy. please can you suggest any ideas to fix.