Oh-oh. More problems for Rich:
Turn off the water to the valve. Open another valve that is down hill from the problem valve with the controller to help drain the mainline.
Unscrew the solenoid all the way out. Be careful not to lose the plunger when you do so. Wrap ONE TURN of Teflon tape around the solenoid threads. Screw the solenoid back in, taking care not to cross thread it. Turn the water back on and observe the top of the valve for any leaking anywhere.
Let me know how it goes.