You should have battery voltage to the one side of the ballast resistor. You have 12+ volts to the starter relay, that is apparently your battery voltage. What is corroded or loose that is only delivering 10 volts to the ballast? Next, the output from the ballast resistor should be wired directly to the "+" side of the ignition coil. You have ~8 volts out of the ballast, but <6 volts at the coil. You have poor connections!
