72 Duster Resurrection

I think the drum only cars had this distribution block:

upload_2018-6-20_13-11-16.png

Which is what I removed from the car before I converted the front to disk brakes.

I think the one I have is correct, but I just cant get it to deliver fluid to the rear. I suspect the internal valve that moves to block a leaking fluid circuit is stuck and I cant seem to get it to re-center..