I’ve dissected a few old coils in the past to see what makes them tick and have found there is usually a small braided wire going from the solder terminal to the end of the secondary winding wire.
The secondary wire is so fine you would need a powerful magnifying glass and hands of a surgeon to track it down. Then you would have to figure out how to remove the insulation in preparation for soldering without breaking it. This is why it was probably fitted with a braided lead during manufacture.
I think this is a Pal/Ranger style coil and you can see the braided lead going to ground. The solder terminal has a similar lead.
