[Arran]

One way to repair a broken wire on a coil is to take a copper strand out of some 18 gauge electrical cord, make a "J" hook or loop, make a splice, and solder the remaining coil wire to it in the hook, and reattach the other end of the new copper strand to the terminal. You could really use anything for this, such as 20 or 22 gauge solid wire, within reason, as it's easier to work with. If you don't have steady hands, or eyes, find someone who does. Antenna coils are pretty forgiving, you can often unwind six inches or more off of them to re-attach the coil to a terminal, and it doesn't detune them, though if the end that is buried under the coil this is where splicing on a pigtail comes in. Some really brave people actually rewind damaged coils, or even output transformers, but there are maths involved unless you can measure how many feet of wire was used on the original.
I don't think that sulfur in the wax is the issue, at least not in Philco sets, the problem there was nitrate based celluloid used as an insulator, the nitric acid leaches out sometimes and corrodes the wire, usually on the primaries of RF coils, though the police band coils in model 60s suffer from this as well, the secondaries are usually fine, and for some reason are on the coil form itself.
Regards
Arran