If you suspect a faulty ballast resistor, you can temporarily jump the 2 terminals, (hotwire them together) now it bypasses the resistor giving a constant 12 volts to the coil. If it starts and runs, replace the old ballast resistor with a new unit. The ballast resistor only protects the coil so don't worry about damaging anything by bypassing it for a few minutes. (unless you have a points distributor but even then it shouldn't be an issue to run it for a few minutes, please correct me if I'm wrong guys..)
