Hunter Pro-C System Squeaking, Low Pressure After Shutdown

After months off, Hunter Pro-C runs but heads barely seep; pipes squeak/hum. Valves shut off/on incorrectly.

Diagnosis

Restriction in the system. Check main shutoff valve—gate valves can stick closed if the gate breaks. If multiple automatic valves show the same symptom, the main shutoff is suspect. If only one valve, its diaphragm is likely bad. Replace diaphragm by removing valve bonnet.