1929 Model A Ford Sport Coupe Misfire

Upon starting the A today I was experiencing a bit of a Misfire, heard a tracking sound and found a plug arcing out on the advance & retard lever. The car has a Simmons head which means the plugs are in a non standard position. New one on me, maybe the weather? All cured by a little bit of insulation tape. I have a modern cap & leads to fit but I like the old style strips!