First of all, have you checked the fuse to the brake lights? If that is good, go find a circuit tester probe(not sure the correct name, you can get them at walmart in the automotive electrical section, they have a probe with a light on one end and a wire with an alligator clip on the other) if you don't have one and test both leads at the stoplight switch. If power goes to one at anytime, your switch is getting power. If both have power when the brake pedal is depressed, your switch is good. As far as replacing a brake light switch, I'm pretty sure two screws hold mine in on the '54
