no power to ballast resistor

yeah, first thing i'd try is the neutral safety switch. And another thing i'll throw in there that others might not think about is the seat belt interlock safety system. It started screwing up on mine and i had to bypass it to get the starter to engage. I do beleive it was only put in cars for a short while in 1974. I'm not sure what car you have though. It should say if you have it above the visor. If not, then that is not it. Good luck with your search