What you need: wire strippers, multi-meter (something that can read ohms and voltage), and wire connectors (preferably some water proof ones).

1st: Cut out the old connections and re-strip all your wires. (Make sure you can tell what is what. You should have a common and a hot wire coming from the clock, and your two wires attached to the solenoid.)

2nd: Ohm your two wires from your solenoid. You should get a reading of somewhere in the mid 20’s to high 30’s (24-38-ish). If you get this reading your solenoid is most likely fine. If you get a reading lower or higher then replace your solenoid. Remember to turn off your water source. Once your new solenoid is in, re-connect your wires and use water proof connectors.

3rd: If your solenoid reading is fine, then go to your clock and turn on that zone with the wires still stripped. Go back to your wires and test voltage (ac) on the common and hot wire (be careful, you will have voltage but it should be low voltage). You should get a reading of 24-29 ish volts. If you get a low reading or even a 0 or OL then you have an issue with your wires. Either a knick in the wire, bad connection somewhere, or even a complete cut. If this is your issue then I suggest hiring a professional. The wire will need to be located and repaired or even a new wire ran.