Is there a way to identify a Control Valve that is already installed in my yard system? I have Hunter PCP sprinkler heads but I don't know how to identify the valves as they were already installed in my yard when I moved into the new home I'm in. I'd like to know if there is a way to adjust them as I have a problem with water standing on 3 different stations on the side of my house that has about a 15 degree slope. One sprinkler in each station holds water regularly even when I don't water for s...