I am currently servicing a 23 zone system. I was unable to open the last 6 zones of the system using the controller. I checked to ensure there was water to the zones by opening them manually. I checked the area and was unable to locate any disturbance on the ground. Also, the blueprints show that the mainline was buried with the wire(s), therefore if the main was struck by a shovel, I would have seen a waterfall. Any suggestions on how to best isolate the wiring fault? I checked the controller with a muti-meter and observed a 24v reading to the affected zones. Of course, the valves have numerous wires and I have located a reading of 8v on the common wire for the last valve that is working properly. Do you think the wire has been split? Any help would be appreciated. Anyone recommend the valve/seloniod tester thats on the market? Looks like a neat tool, wondering if it is worth the $80.