I had same problem, I switched off electrics pulled out the m/c then laid it on its back! I know dont think that was neccessary, as the small tubes can be accessed from the front, I removed each small plastic tube (3No) two on a plastic tank and one on the visable pressure switch, with the help of a spare piece of tube I blew thro to operate 2No p/switches you should hear a positive click from both, the third tube (pink) operates a widget on the inlet valve at the rear i got a clunk, continuing to use the spare piece of tube i also blew thro the 2 plastic tank connection nipples to which the 2 were connected I then blew up the tube to the hidden outlet of the tube which runs up inside the m/c which is connected to the front p/sw this was clear, because i could, I also cleaned filters on the water supply hose although they seemed okay, I did not find anything specific but its working again, once working i used a proprietary cleaner that was a week ago, hope this helps
johno
October 2006