hi wendy your problem sounds as if it is a part called the pressure switch whitch either needs replacing/refitting or the clear or black thin hose goin down to the bottom of machine needs to be checked for wear/holes in it. the pressure switch is mounted at the rear left hand side of appliance but the top cover has to be removed ( part will either be black & gray or red & gray round in shape& has four wires going to it.)REMEMBER TO SWITCH OF POWER BEFORE DOING WORK ON APPLIANCE.hope this helps
colin.
November 2008