it could be a blockage in the pressure system,as water enters,it pushes water up a tube to operate a pressure switch,this in turn sends power to the timer advance motor,the pressure chamber gets blocked with gunk,all you have to do is remove it,clean it out,then try again,i worked for hoover for twenty years in glasgow,and we cleaned the chamber out on all service calls,hope this helps you
gts, August 2010