It will also be interesting to see whether people find convenient ways to remove the epoxy or whateve that potting material is, without damaging the earphone housing.
I should say that heat is the only practicable means of 'depotting', given that the potting compound is known [from 'The Motor Cycle' article above] to be an early Araldite epoxy.
There are only one or two solvents that will work on cured epoxy resins, and they are nasty enough to
require a fume cupboard. Even then, it takes some time. Not sure if they'd affect the phenol-formaldehyde resin [Bakelite] casing as well, either.
For re-potting, there are any number of different non-corrosive 'electronic potting compounds' available these days. Check the RS Components or Element14 websites for examples.