Yes. Ballast is taking battery voltage down to whatever it is at the coil so it will be hot. If it now miraculously now runs, you had a dirty firewall connector. I would remove it and clean it as best you can.
Well no, you did it. You cleaned the connection "enough" when you disconnected it. I would disconnect it again and clean all the brass terminals best you can. Now you see why we always say those firewall connectors can be the devil. lol
no, not the bulkhead connector, I disconnected the pin connector the ignition switch wires go into.
I just touched the bulkhead connectors with the probe and it lit up the test light.
I would like to take out the bulkhead connector and clean them all, but when I tried to do that before, it would not come out and in the interest of not breaking it, (since it is 50 year old plastic) I stopped.