Nilfisk c 120.3 cycles on and off about 20 times a minute when lance is not in use. There are no leaks on the outlet side and the intlet side supples ample water. There is no air in the outlet hose. It has definatley been purged adequately. I guesse there is some kind of pressure valve that operates a switch to turn off the motor when lance trigger is not depressed. If so, does this valve generally need replacing?