Mark, inspect the vacuum hose between the check valve and the treadle vac. if its wet, it is a sure sign that all is not well within the booster. heres what the manual says about testing a treadle vac: with the engine stopped, and the transmission in neutral, apply the brake several times to exhaust all of the vacuum in the system. depress the brake pedal, hold foot pressure on the pedal, and start the engine. if the vacuum system is operating, the pedal will tend to fall away under foot pressure, and less pressure will be required to hold the pedal in the applied position. if no action is felt, the vacuum system is not functioning. stop the engine and again exhaust all vacuum in the system. without starting the engine, depress the brake pedal and hold foot pressure on the pedal. if the pedal gradually falls away under foot pressure, the hydraulic system is leaking. if the brake pedal travels to within 1 inch of the toe board, the brake shoes require adjustment or relining. a faulty vacuum check valve can be tested by shutting off the engine and after waiting several minutes, applying the brakes. there should be sufficient vacuum reserve for several applications. with the pedal going to the floor (or almost): A brakes need adjustment B air in hydraulic system C hydraulic leak in lines or at the wheel cylinders D fluid reservoir needs refilling E cracked drums F power brake leakage at: 1 compensating valve or seal 2 hydraulic plunger seals 3 outlet fitting 4 sand hole or crack in the master cylinder there are any number of places that can rebuild these units. for what it is worth, Karps in Upland, Calif. did mine about 10 years ago, and i haven't had any problems with it. the cost was $200.00.