im having trouble starting my wd tractor .I replaced everything in the distributor ,points,condensor, new rotor and cap,coil,plugs and wires . it is converted to 12 volts .it was running rough before this summer and I readjusted the points and quit.it had a distributor from a international b which was change many years ago. now when I crank it over and put a test light on the coil it lights up on both the positive and the negative of the coil ,its a new coil, but it still doesn't fire,could it be that the distributor has shorted out.it seems that it doesn't load the coil to fire to the plugs