<font color="red">It is important to turn off or close the water main and drain the irrigation line completely before disassembling a valve. Open the bleed screw on the top of the valve to relieve any remaining water pressure.</font id="red">
To disassemble the valve, depending on make and model, first you must unscrew the solenoid from the valve (make sure water is off). Once the solenoid is removed, simply remove the screws on the top of the valve, or if it is a jar top valve, simply unscrew the whole top of the valve. (Note, if you have metal screws on top of the valve, it is NOT a jar top valve. Once the screws have been removed, simply lift the top off of the valve. Fairly easy even for a novice.
Valve repair kits are available that supply the important parts to the unit. Despite the daily hammering and rushing of water through an electronic valve, they are reasonably durable. With proper maintenance and repair, electronic control valves will sustain the integrity of the irrigation design for years.
If you decide not to fix the problem yourself, you are probably looking anywhere from $40-60 an hour labor, plus parts. Generally, a valve replacement shouldn't take more than a couple of hours.
Tony Posey
Ridge Run Landscapes