[Chuck Schwark]

You didn't mention in your original post if you had checked all coils for continuity.
Philco impregnating wax was(is) notorious for corroding the copper windings, due to the high sulpher content of the wax.
Over time moisture in the air combines with the sulpher compounds and forms weak sulphuric acid that eventually attacks the exposed copper at solder lugs and in the windings themselves. Tiny green-ish spots to look for.

Chuck