John- the distribution block I have now is a "supposed" good used. I bought a new one also but saw some threads about the new blocks having problems. I got the new block from Inline Tube, as well as the stainless lines.
I have heard (and suffered this once at a repair shop), that a prop valve, especially when old, can move/stick durign bleeding.
Those valves never see the maintenance or replacement like the MC does, and they won't perform full travel on the valve unless one section of the brakes gets opened fully, which happens only during bleeding or brake system failure.
Yeah, they see some 'maintenance' and new fluid when brakes components are replaced, but they're still an old cast-iron part with rust inside.
Just a possibility to consider.
I don't know what material the valve is made of but the block itself is Brass not cast iron, I imagine if it were iron it would rust itself stuck in no time.
RT , the distribution block is just that , a distribution block , 67 to 69 cars used the same block disc or drum with a residual valve in the line to the rear, all that changed in 1970.
