Solenoid question

[John Nash]

When I rotate solenoid (to manually start that zone), that zone does not turn on. Does this mean that the solenoid is bad or is the valve bad or about to go bad?
This happens for 4 solenoids in my system. They all work fine with the timer. I am not able to turn them on manually at the valve. These don't have a screw that I can turn to turn that zone on so I was testing by turning the solenoid itself. This approach works for remaining solenoids in the system.

 

[WorthFlorida]

There may be debris inside the valve but otherwise all of them should function the same by just turning the solenoid to get water flowing. Perhaps with these valves the diaphragm may have gotten a little hard.
All a solenoid does is move a plugger maybe 1/16 of an inch about the same by unscrewing the solenoid or just giving it a 1/4 turn. Hunter has troubleshooting and repair videos. But then again, do not fix what is not broken. If they're working with the solenoid leave it alone. If all your valves are the exact same type, then buy a few diaphragm rebuild kits before opening them up to clean or replace seals and diaphragms.

https://www.hunterindustries.com/videos/cleaning-diaphragm-hunter-valve-quick-tip