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No one agrees with me but you can coat them with Super Corona Dope, a very high voltage insulation that looks like clear finger nail polish from MG chemicals. Once the cracks are filled wrap with radio controlled airplane very thin fiberglass cloth & recoat. What is the resistance from plug wire to ground? Once the coil is clean look for pits where the coil may have arced to ground. There is two coil windings, primary &; the secondary winding, the wire used is finer than a humane hair & damaged easy. Running without having the plug wire off the spark plug has produced energy & will arc to the magneto plate.
Also don’t forget the capacitors, they fail too & will not give a good spark. They are 2 pieces of foil separated by wax as an insulator. The wax shrinks with time & shorts out the foils.
Top seal may be bad blowing fuel on the magneto causing no spark too, was it wet?Capacitors are challenging to test without an ignition tester like a Mercotronic or Stevens. You can do simple tests with an ohmeter; test for a direct short (shouldn’t be shorted of course…) and then you can test with an analog meter and watch for just a bit of a bump of the needle on the 1k resistance scale. The needle should deflect just a bit and then return to rest. But these are simple basic tests that cannot indicate a cap which will fail under load. Usually they are just replaced if suspected bad.
I have resisted answering your question about the variance in the secondary resistance. I would think they should be the same if they were the same brand/vintage/model of coil….but I have seen many instances where coils will vary like that and still work. Like I stated in my first post here….if it were me I would clean things up and try running the motor or just do a spark test. Simple, quick and informative. If this is a motor that you want to build to be a daily runner then you will most likely want to replace coils, condensers, wires and points as the budget allows and parts become available.
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