I acquired a JD model B from a friend when he died and not sure what all he has modded. I used it for a few years in parades and for grading our private road but now it will not stay running. It fires up fine and runs great but then just dies. Seems to have plenty of fuel flow to the carb and the carb looks clean and good. It also fires right back up but still will not stay running. I pulled the mag open and the points, rotor and cap are pretty worn and need replacing. It also seems to be bypassing the mag and using a 12 volt coil and just the points in the mag to fire the coil. Is it possible to update the ignition system to something better? Is this a common issue? It really seems to just completely die like the ignition fails, when I check it I still get spark but then it also always fires right back up. I plan on repairing/replacing the ignition system and plugs but the cap does not seem to be available until at least Sept. and I am not sure why the individual 12 volt automotive coil. I also do not want to spend $$$$ on the model C mag if there is a better solution. HELP.