Bad KH prop valve

Does any body no if you can fix a KH prop Valve? I went to bleed my brakes after doing a 74 dart disc conversion on my 65.The front bled fine but when i went to do the rear there was no brake fluid flow. I had fluid at the inlet to the kh valve but when i disconnected the brake line to the rear nothing..i even had my son press on brakes. still nothing,, I removed the spring at the bottom and there was fluid. Should i just install an aftermarket prop valve?