power brake problem

[David Pozzi]

The pushrod from pedal to the booster plugs in to a plastic "reaction valve" inside the booster. It sounds like this valve is broken which is very easy to do when the booster is not in the car. The reaction valve lets air enter the booster when the brakes are applied, this air pushes on the diaphragm.
You can probably use your booster as a core and get a rebuilt one locally.
David