SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I have 4 in-ground stations using Toro 250 valves with bleed screws and flow controls. Water is about 42 PSI. 1 station with 4 sprinkler heads, does not function at all, while other 3 stations operate all pop-up sprinkler heads properly from the B Hyve controller which is 2 years old. None of the 4 are drip systems. I have performed 5 electrical tests with Klein multimeter for AC voltage and ohms at 3 separate times. All 3 sets of tests confirm that the AC volt power and Ohm continuity/resistance are within proper limits. So there is no problem with voltage or resistance or wiring from the power pack to the controller to the valve or with the solenoid itself, which performs satisfactorily. I have re-stripped the common and live wires and replaced weatherproof screws and caps. I have removed the solenoid and cleaned its spring and piston, as well as removed the valve cover and disassembled the valve diaphragm and cleaned all parts including the flow control valve which I tested. I have re-assembled all and there are no leaks. When I turn on the controller, there is noise from the solenoid, indicating to me that it is receiving electrical current and is operable. The station only works if I unscrew the bleeder valve to the point where it is almost ready to pop off the threads. At that point, the 4 sprinkler heads pop up and operate properly. However as soon as I re-tighten the bleeder screw, the station shuts down, the sprinkler heads drop due to the lack of water pressure, indicating that the bleeder valve has stopped water from entering the diaphragm and pvc pipe. Any ideas on what might be the problem? I noted that the white plastic ring, part # 19 in the manual, does have several hairline cracks, but is not broken or cracked. Thanks.