alan50, a professional instructor once told us that if this knob is turned all the way out and withdrawn (there should be a sturdy needle attached to it), the jet of water "scrubs" the valve and takes care of problems like you describe. I mentally filed away the information but never had to apply it so I cannot say if and how well it works.

Sounds like a possible solenoid problem. If they turn on manually, but not w/ the controller, swap the solenoid from another valve and see if the valve in question comes on then....if so, replace the solenoid. (When you swap w/ another solenoid for testing, the problem valve will change "station #'s". If you use the solenoid from the valve on station 3, the problem valve will have to be tested as station 3.....the solenoid will keep the same original station # due to wiring). Good luck