I have a 6-valve system and two of the valves will not open when they are supposed to. There is another valve connected to the common ground with the two defectives ones and it works fine. If I turn the bleed screw they will come on. Then I can close the bleed screw and they will stay on for the proper amount of time, then shut off with the timer. I tried replacing the solenoid, but they are still doing the same thing. Any ideas?
