Alright, first off please forgive my inexperience. I have puddle forming around one of my sprinkler heads when its retracted. It seems to be a slow leak, as I can't hear or see any flow coming from it, but there's definitely water coming from it when it's not supposed to be. Is this a symptom of a bad head or a bad valve? If a valve, does each head have a valve under it or is it one valve per zone? Thanks in advance for the help!