i know it sounds odd but this is what the faulty booster in the Mazda did.Would this not be against the common sense? Not saying it didn’t fix your problem, but what would the logic explanation be for the booster being the problem?
I never examined the old booster, just replaced and brakes came good instantly.
Prior to swapping it out the pedal would seem hard with the motor off however once started the pedal would sink to the floor and braking was pretty much non existent
It did happen after I had the car apart for repainting so whether something worked its way loose or other I dont know, it just failed