I think I would pull the coil anyway, just to clean out
the old tar potting and clean the contact on the coil.
Some of those had glass insulator
tubes around the coil secondary terminal, that often
are broken.
Here’s a magneto from my A-45 that I pulled all apart.
I can’t remember if this one originally had glass insulators
or not, but after I attached the new plug wires, I packed
some “fish”? (insulating paper used on generators, etc.)
paper around the secondary connections.
Prepare to be boarded!