Gibsonette Filter Resistor Cooking

[Helmholtz]

So it's a whole system choke?

Yes.

Another consideration is that just a few shorted turns wouldn't much change the DCR of a choke having many hundred turns.
OTOH, if most of the turns were shorted, inductance should be close to zero because of magnetic coupling.
So I think it's a low inductance choke using few turns and thick wire.