While I was waiting for any responses, I tried to get the valve to flow. Screens were rather rusty and crusy, so I leaned the washer on it's front and filled the inlets with toilet bowl cleaner. Once it turned green, I knew it had done what it could. Blotted the stuff out with paper towels and caught the remaining liquid with a glad bag when I righted the washer.
Got the screens out and did the back flush by using supply hoses. One to the water supply and other to the drain in the washer box. I figured out long ago that left disconnected, an inlet valve will backflow on it's own.