I have a model CSV12560-1, an above ground jet pump, a 40/60 pressure switch and a small diaphragm pressure tank. The system has worked great for 5+ years. A couple times recently the water system shut down, no water. I went out to the pump room and tried the simplest thing: turning the little lever on the pressure switch and the pump started and every thing was fine. This happened a few times. I figured I needed a new pressure switch and installed one. The new switch is exactly the same as the old one but now the system operates like there is no CSV. The pump cycles between 40 and 60 over and over as I can see it on a gauge.