Question
Everything else seems to work, what do you think prevents me from operating an individual zone manually?

Answer
Hey Frank, if when you try to turn it on manually, does the display start to flicker and then go to "off". If it does, then there is diode in the control panel that needs to be replaced. If it works automatically, then there should not be an issue with the valves, or wiring.If you could give me more information it would be helpful. Does the system operate automatically? Does the display flicker when you try to turn it on manually? How are you turning it on manually? Are you turning the dial to the zone first, and then putting time on it before you hit manual? Does it work semi- automatically? Let me know, thanks and have a great day.