My dad has a 1987 Buick Grand National GNX that I am looking to fix up. He’s not that great at maintaining things, so the car has been sitting in the garage for a year due to the brake light being on. Took it to a mechanic to get things looked at and they said there was nothing wrong with the brakes. Driving the car home and the brake was completely gone. Luckily no one was hurt, but now the car is inoperable. Had it towed to a different mechanic and was told that the power boost break system is broken. Any advice on how to get this fixed? is the power boost system unique to the GNX? The car is completely original and I don’t want to do anything that would change that. I would also like to know if there are any good mechanics that specialize in the GNX. I’m located in California. Thanks.