That can be a toughie.... first start by checking continuity to the valves and see what the resistance is... at both the clock AND at the solenoids. If there's more than a couple of Ohms difference, I'd start looking at the wire connections. Did you splice the wires between the clock and valves?
Next is the solenoid port. Some valves inherently have critical flow problems in the solenoid chamber (be sure it's clear) and need a "boost" (opening the bleeder or solenoid) when the diaphragm gets stiff when sitting unused. Fr'instance, like when you leave the system off for any extended period of time. Sprinkler systems are like cars... ya can't park 'em and come back weeks or months later and expect them to work perfectly.... every time. Unless you blow your system down for winter, run the valves a minute or two once or twice a week to keep it "lubricated".
Bill
The Irrigation Specialist Mfg' Az.
Please check my website and you'll find what I do and the unique tools I make and market.
Real timesavers, especially the Suck-Tube and Krik-It.
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