About a week ago I noticed that I've lost my power brakes on the 70 XR7. I have to really put pressure on the pedal to get a solid stop. I asked a guy at the parts store what he thought it was (he knows older cars) and he said that it was probably the brake booster. I checked MustangsUnlimited and the price tag was $250 smack across the face! Oddly the parts store said they had it for only $115, I assume the parts store will have inferior parts and fit??? Anyway, can anyone weigh in with their opinion that the brake booster is probably at fault here, and if so how big of a project am I looking at in fixing it. A side note I've also noticed that when I start my car up after it has been running for a while and sat briefly - that I'm getting sound coming from the back of the engine compartment near the firewall - it almost sounds like a steady electronic alarm humming sound. (like early 80's cars when you leave the lights on or keys in the ignition when getting out) It's not screaming loud but it can be heard inside of the car with the engine going. Could this be related to the brake situation?? Any help with what's going on\buying MustangUnlimited Vs. Parts Store parts\how to fix this problem would be greatly appreciated.