For 11 years my in-ground/gard

For 11 years my in-ground/garden sprinkler system - 8 independent solenoid valves, sourced by a large underground cement tank and pumped by a Davey Torrium has been working just fine. Went away for a month with system still on auto start according to the timer. Upon my return, system stopped. On inspection, pump fine, but huge hammer type vibration in solenoid 7. Stripped it down and found no obvious problem.
Vibration still there. Any fixing suggestions most welcome.
Cheers

Vibration is most-likely related to a loose part somewhere in your system. Could be a washer, stem, check valve, interior gate valve part, etc. However, that should not stop the entire system from working ( unless it is a stuck check valve ). Look between valves and the pump. Any check valves or shut off valves in that section of the pipe? Make sure they are OK

Also, turn the system ON to generate the vibration. You should be able to follow the noise to the source

Milo