Unfortunately ignition testing requires test equipment the average person can’t afford to buy just to locate a problem. I used to do ignition work for money and have a Mac ET975 diagnostic oscilloscope, a Uscope, and a thermal camera. That’s over $2000 dollars worth of equipment, but with it you can “see” the reluctor output, the primary and secondary voltage patterns, terminals, coils, and boxes overheating and find out exactly what’s happening. I hate to say it, but there’s no other way to do it other than throwing money and parts at it.