Brake warning light, Amp light

[CheeseSnake]

I bought my car already built in 1998, and I'm going through it now that I have time to do a lot of upgrades. Anyway, the guy I bought it from had overheated the brake fluid due to the proximity of the proportioning valve to the headers (that was his story) - there is about 2" of clearance between the prop valve and the headers at the front of the drivers footwell. Since I bought it, the red brake warning light has been on whenever the car is running. There is a small red switch screwed into the prop valve with a plunger on the prop valve side and two pins on the other side with wire #156-blue going to one of the pins. There is no ground directly to the prop valve. Where can I get a new switch, and how should I test it? I assume it is meant to signal loss of brake pressure.

Also, the amber amp light. Is this light supposed to be on all the time with the car running? I don't remember it being on but I cant start the car right now ( carb and a lot of other stuff is off the car at the moment) and the light is on when I turn the key to "run". Is this normal, and if so, where does the light get it's signal from?