hi, i have a powercraft jetwasher sold by aldi's but made by karcher, to all intense and purposes it is a karcher, i got it march 2005 it has developed a problem when the water is on and the power is turned on it keeps making a ''thump thump thump '' sound and litterly if you pick it up off the floor you can feel it lumping about as if the air inside is being compressed, when you press the trigger on the lance the thumping noise stops, but the jet of water is at a slightly reduced pressure, some people have mentioned the pressure switch and the hard water lime scale problems anyone have any ideas, regards dave