I have a 3 zone sprinkler system that sticks in zone 2. My zone 1 and zone 3 both turn off when the timer runs to 0 minutes. I have to turn off my entire system to get zone 2 to stop sprinkling. I can find only one control valve in a round housing in my yard. Should I have 3 of these control valves in my yard, one valve for each zone? If I do have only control valve for all 3 zones, should I replace the diaphragm in the 1 control valve housing that I have been able to find in my yard?