when applying the brakes with even a slight amount of pressure, i feel a pop in the brake pedal and the brake light comes on. and stays on. then once i'm stopped if i pump the brakes firmly 2 or 3 times i feel it pop again and the brake light goes off. at first this was only happening every once and awhile, and now its happening everytime i use the brakes. my first thought was the master cylindar. than i got to thinking, maybe its the combo valve...the pin not recentering? what do you guys think?. i'm hoping its the master, becasue i can get a new one for around 50 bucks, but if it the combo valve..i priced on out at 200 plus dollars!!!!