i have had the same problem, the filter housing was clear and no blockage anywhere, so i removed the pumps and housing from the machine, then i removed both pumps from the filter housing, each pump has three screws, once removed you can seperate the green impellor from its housing, behind there was aload of slim/sludge once cleaned and dryed and put back together the machine works fine. both pumps need to be cleaned.
michael jones, July 2010