Automatic sprinkler valves that won't shut completely? Try taking them apart and cleaning them out.

As Sean Stefan of Sprinkler Daddy ( http://www.SprinklerDaddy.ca ) shows in this video with an Orbit Automatic Sprinkler Valve, sometimes dirt, pebbles, or rocks can get into the valve and prevent it from closing. Your first option with a disfunctional valve should almost always be to clean it up first before you replace the entire valve.