I have a High Flo gold series 2.1 gpm pump on my sprayer. It is supposed to cut off at 60 psi. It has stopped cutting off and now sprays out of the middle nozzle with the boom valve closed and the pressure at 60 psi. If you close the bypass all the way it will go all the way up to 100 psi and the hand wand pops off. The guy I talked to at Fimco said the pressure switch was bad and they sent me a new one. It didn't fix it. Anybody got an idea what might be wrong?