Went to a job tonight. Master valve (DV100) diaphragm needed replaced. Went ahead and replaced entire top half with a DVF100. All zones worked like a champ. Then comes zone 6. The last one, but the closest one to the controller. I test my voltage at the clock, 27.5 volts. 521 leads me to a rats nest of splices wrapped in duct tape in the flower bed so I fix that. After the splices, I am getting 24 volts about 20 feet from the controller. At some point in the yard, the installers went from 7 strand multi-line to 3 strand multi-line and crammed 2X1 inch valves in a 6" box. Zones 5 and 6 are in the same box. I am getting 27.5 volts to zone 5, but nothing at zone 6. This is multi-line wire in a single wire sheath. Common sense tells me that it would be very difficult to cut just one wire (zone 6) but not the other 2 (I know it is still possible). My feeling is that the splice came undone at the conversion from 7 strand to 3 strand. The zone works if I run a whole new 18G valve wire to the controller. I have decided to replace the valve wire altogether. Am I missing something? 106* heat does not lend itself to hand trenching.