Brake Light Problem 99 Suburban

I am experiencing a problem with my brake lights where the lights come on when you first push the pedal go off when the pedal is half pressed and then come back on again. I am thinking that the problem is with the break light switch. What do you guys think? If it is the break light switch how do you replace it? I reached under the dash and found the switch I could pivot it forward but could not get it to release.