Question
Zone one on my Toro TMC-212 does not run. This is the case automatically and manually. The other zones work in either case. What do I do about it to fix it?

Answer
If a zone doesn't work it is typically an electrical issue.  I would check the station terminal (see if it is putting out the proper voltage) check the zone wire from the timer to the valve.  Check the ohms to make sure there is no open circuit.  Last check the valve solenoid of the valve in question.  The solenoid is typically the most common cause of your issue.