[Arran]

 Clearly something went wrong with the speaker field coil in this set, which was why they attempted to make a choke or of a small transformer. Either it was damaged by a shorted filter cap or the winding just failed mechanically for some reason. In any event it's the inductance that matters not the DC resistance, the DC resistance of a proper iron cored choke can be lower then a type H Philco speaker and still work as long as it has the same number of Henries. It would be easier just tracking down a replacement H series speaker rather then rewinding the field coil, but if the original speaker is otherwise intact, and you can get the bobbin out of the frame to rewind it, why not give it a go just for the experience?
Regards
Arran