72 Scamp No Brake Lights...

One thing you should know is that the contacts in the aftermarket blinker switches tend to recede into the crappy nylon switch bodies when they get warm. As when the brake-lite sw sticks on, or the hazards are on for a long time, or if you are in tha habbit of riding the brake pedal. You will see it when you separate the two halves of the switch. It can happen on the factory one as well but it takes about 50 or a 100 times as long.
I recommend you check this out before you spend 50 hours looking for an electrical problem that may not exist.