I have a '69 Malibu with power drum brakes. I'm going to be replacing a leaking master cylinder, and while in the process I'm considering whether or not to replace the power booster. I've had the car since the early '90's and the brakes have never been much to brag about, even after new wheel cylinders, hoses and brake linings a few years back. Biggest problem is a real low and soft pedal, which i assume to be the master. The booster appears to be original and I'm unsure how to determine if it needs replaced or not. Anyone have an guidance?

When your booster fails its likely that you will hear a hissing( vacuum) noise from under your dashboard. If you don't hear that its likely your booster is still good..