the headlight on my 1983 XVZ12T will not come on. We checked the voltage there was 4.5 volts at first, then we started to trace the wiring back and it jumped up to 12 - 13 volts. I have checked the voltage at the switch and there is 13 volts. the bulb is good, but the light still will not work. could it not be getting the correct amperage? We are stumped!!