Reply to "Brake Booster Check"

When I broke a part in the booster, I suspected but could not confirm no boost until I actually started the engine and put pressure gauges in the output lines. With engine off (or with broken booster), line pressure was 450-550 psi. With engine running, line pressure was 1100-1200 psi once the booster was repaired.Incidently, this is also an excellent reason to change ANY rubber brake lines (good for about 1500 psi when brand new!) to 3000-psi-test Aeroquip braided-stainless!
How you check the system at home with booster out of the car, I have no clue. Some manuals aay 'listen for air exhausting from the vacuum diaphragm valve'(under the dash). Others say to check vacuum levels. None worked definitively for me. Suggest you take the booster and master cylinder to a specialist shop that works on such things, and let them test it. This will be a real time saver, if not a money saver.
FWIW, the nose section valve that protrudes into the cockpit under the rubber boot was cracked on mine, not allowing vacuum to develop in the big can. No other symptoms.