Good idea to try another (known working I hope) controller. I have fisher, but I'd check where there is a wire going into the truck cab fuse box. Is it tight and clean? I'd check the inline fuses in the harnesses under the hood, are they good? I'd check the ground on the plow, not so obvious on the fisher, to the rear of the pump box, is it clean and tight and greased? I'd pull the cover off the pump housing and check the solenoid. They just die, occasionally an intermittent death. Try to jump past it and see if the pump runs.
I'm not a mechanic, I just try the obvious weak points, and I've not even seen a western plow. I do know how frustrating it can be when it won't function. Perhaps someone who knows something will add some ideas.
Guess you ought to check the pins where the controller hooks up also, I've never had a problem there, but who knows?