Superior Contols 600 valve replacement
Working on a 9 zone 1" system, and at least two of the valves need to be rebuilt. When I was doing a Google search on them, after finally identifying them, I found a thread on here recommending not repairing them, but replacing them. The system is 11 years old. 6 of the zones weren't working because of wiring corrosion. I got the wiring resolved, but have flow issues in two zones. No leaks that I can locate, and backing off the solenoid screw makes them work better. Loosening the 4 of the six screws on top while the water is still turned on also pressurizes the system and activates the pop-ups.
So my question to the experts here is rebuild or replace? If replace, with what? Should I replace all 9?
The system is in So Cal.