[Chuck Schwark]

Since L300 is a simple RF choke with a phyisically small winding, I'd look for the wire break at the connections to the wire leads.

Philco gives no inductance value for this coil in any Philco Parts Catalogue I have.

If you have to unwrap a few turns to get to the break it's not critical. Or if the break is way inside the coil, just re-wind that small coil with the same gauge wire to approximate the number of turns. It does not have to be pi-wound like the original. Just keep the turns "globbed up" in the center of the form.