hey mark, the points act as an intermittent ground for the coil. If the coil isn't sparking then look at the points
if you have a 12V test light or a voltmeter, go to the wire from the coil to the dist. As you open and close the points the light should flash on and off. If the current is cycling on and off then you should have spark and if not then you issue is with the ignition coil
