[Arran]

Steve;
O think that you can rebuild a Philco speaker by pressing the pole piece out, that part in the center of the voice coil, and the field coil will come out afterward. If the speaker has a dead field coil you really have nothing to lose by trying, of course you will have to remove the cone first but acetone will take care of melting the glue holding it around the outside edge.
Regards
Arran