1968 Dart Brake and Booster issues?

Originally the distribution block contained a safety switch that would flash a warning light on your dash if it detected an imbalance between the front and back brakes. The way that works is by grounding the attached switch. Think of the internals as a piston that moves left or right when detecting an unevenness. In the center there is no path to ground for the switch, the circuit is "open". When an unevenness occurs the piston moves and grounds the switch and blocks the offending low pressure side so no more fluid is lost. When "tripped" this way, it is often needed to disassemble the block to "re-center" it. Original distribution blocks and proportioning valves and lines are available. Sorry about being so "wordy".