Somewhere I have a stick with a hole in the end coming out at 90 degrees that fits on a garden hose. If you were to stick that in the exit and flush the valve area with water with the valve open, it should dislodge anything stuck in the valve. My valve would not shut off because the seal got caught by the blade. This was probably a result of something stuck in the valve that pushed the lip of the seal the wrong way and the blade held it that way. I would leave the valve open so the seal does not take a set. Here is a photo of my valve.
Here is the thread on my valve replacement issues as well.