I have a little problem with my brakes. It`s 1970 A-body duster. It has original kelsey hayes 4 piston calibers. When i put the vacuum hose from the intake manifold to brake booster, brake pedal wont come up at all. When i push the pedal, car stays still and the brakes are on. When i disconnect the booster, it takes a little while and the brakes start to work again. Pedal comes up very slowly. So the problem seems to be in the booster? Anyone else had this kind of problem?