Dun,

First check for electrical shorts to the valves or loose connection at the valves or controller. When redoing screw caps that wires go into, use the waterproof types with gel in them. If this doesn't work let us know. GL Aloha

This is going to be a valve issue. Most likely its a piece of debris stuck in the diaphragm. You can try flushing with the bleed screw, but often debris can become stuck to the soft rubber of the diaphram, in which case someone will need to open that valve and remove whatever is preventing the diaphram from fully closing. You may also need to replace the diaphram if it has been damaged or excessively pitted by debris. Good luck!