Stop in for a cup of coffee

How often do the brake diatribution blocks mess up on an A body? Getting fluid out of the master cylinder (replacing soon) but cant get any out the lines downstream. Will check the rubber hoses but this thing is acting wierd.
Not sure how similar the dist valve is to a proportioning valve. They get dirty, stuck, seals go bad..I made one good one from 2 dysfunctional. They do sell rebuild kits