Coil Problems?

This is my first post on this forum. I would like to thank all of you for your previous posts. I have been fighting an issue with my 1986 SN 2001 and your input on previous threads has been invaluable in finding my issue.

I purchased my boat about a year and a half ago. I have always loved Correct Crafts, but have not owned one since the early 80’s. This boat runs great about 99% of the time. It is that 1% that has caused me to pull my already grey hair out. I think I have it figured out and thought I would post here to help anyone else that may be seeing the same thing.
The first issue was when we were out cruising the lake. The boat just died and would not restart. It would crank, but no fire. I have not worked on a points and condenser ignition for a while, but I was able to quickly determine I was not getting spark out of the coil. I replaced the coil the next day and it started right up. The boat ran perfect the rest of last season.

This year I went out and ran down the lake for about 15 minutes and we stopped to swim. After about 20 minutes the boat would not re-fire. Again, I diagnosed it to a bad coil. I could tell that the coil had gotten very hot. I found this forum and started reading about ballast resistors, etc. I replaced the coil again and all was well until the next trip. We did almost exactly the same thing and the boat did almost the exact same thing. This time I had a spare coil. I put it on, but it did not fire right up. After fiddling with it for a while with the cover open, it fired and I thought it was just a loose connection. I went home and looked over everything and decided I must be using the wrong coil because I did not see a ballast resistor. I went and bought one for $7.99. I now thought I had it. Then last night, we went out and ran the boat down the lake. I stopped and shut it off right at the ramp. Much to my disgust, the boat would not start again. I was really confused. I changed the coil again and it still would not fire. That was the big hint. I had another issue. We went to the park at the lake and ate dinner and just before we left to go home I decided to try to start the boat. Guess what, it started right up.

Today, I got serious and tested all of the coils that I have taken off of the boat, they all tested good. HMM, I started looking around and checking voltages and determined that the input voltage to the ballast resistor was a little low. I pulled off the circuit breaker cover on the back of the engine and much to my surprise there was a ballast resistor right there on the top. I now had 2 ballast resistors on my engine. I checked the voltages across the original resistor and found that it was only dropping the voltage by 1V. My guess is that ballast resistor was the problem all along. It would heat up and open the circuit and the coil would not be getting voltage causing the no spark condition. I now have 3 coils that are all good. When all it took was one $7.99 part. I hope that helps someone else.