gecko1953, the bleed or relief screw opens a small port which empties the chamber on top of the diaphragm. On the opposite side, the plunger of the solenoid opens a similar port when an electric current passes through. I suspect that this latter port is blocked. With the water shut off, unscrew the solenoid (do not lose the O-ring seal)and turn on the water. Water should squirt from the port and the zone should operate. Then there is a path drilled through the valve body to lead this water away. That may be blocked. A very skinny flexible 'probe' is useful for clearing these blockages. If this does not work, someone else will have to take it from here.

ronalawn82, TY ! This makes sense, I will try it when I get home from work today & let you know how it goes.

ronalawn82, I can now sleep peacefully at night again ! I cleaned out the path as you suggested & after some groaning & shaking, the popup heads came on & the zone now works fine. Thanks again for your help.

Gecko1953

gecko1953, I quite enjoyed the trouble shoot.
A WIN/WIN situation!