Bosch classix dishwasher stuck mid-cycle?

My dishwasher is stuck mid-cycle, with the On led flashing and the rinse aid led on all the time. Turning it off and on again has no effect. I've tried tipping it on to its left-hand side to let water drain out - no effect. I've taken the left panel off to reveal the plastic unit with waste pipes, inlet pipe plumbed in. There is an awful build-up of grease at the inverted U bend at the top, but can't see how to unblock it - is this likely to be the cause of the problem? I get the feeling that some kind of float valve is getting stuck. Unfortunately I can't find any nameplate giving the model number. Any help greatly appreciated - fed up of washing up!! Thanks, Tim