u/bhwashington

A zone that had been working well for a while suddenly started failing at one of the sprinkler heads. I was able to temporarily partially correct the issue by changing the nozzles to lower flow. It has stopped working again. I put a pressure gauge at the first sprinkler, and only got 20 psi. It doesn't change much if downstream sprinklers are capped or not. My first guess is a valve issue since there's low pressure at the first head, but that is purely a guess. A picture of the valve for the zone is attached. Suggestions on further troubleshooting (or ID of the valve for further research)?

The system is anywhere from 6-30 years old, and I'd lean towards older based on the heads clearly being placed before trees grew much.