Jack, you state "and there is 24V AC current at the valves."
Is this all 3 solenoids at the same time?
Is it actually current, or just voltage there? Voltage "ain't worth a damn" of there's no current to go with it.
Did you read the voltage with the solenoids disconnected or while under load? (Very important!)
In any case, each makes a big difference as to what's going on at each solenoid. Make sure the wires are not crossed, i.e., the common wirre is actually the common, and the resistance reading from the clock common to each of the valve terminals for the whole system is approximately the same.
Hopefully you have all the same type solenoid.
Last, read the working voltage at the clock as well as at the valves, individually. Lower voltage at the solenoid depicts a bad connecton somewhere.
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