[etech]

One other thought came to mind also, which I will mention for your consideration. Many times a field coil winding will fail at the connection point where the external wires attach to it. Since your field coil is already open, you cannot do much harm. You may want to carefully slice back the insulation around the field coil where the external wires enter, to see if there is a bad connection where the windings attach to the external wires. I'm not sure about these, but some field coils actually have small terminal lugs inside that the fine field coil windings are soldered to. In general, I have been lucky about 25% of the time in finding the open at these connections, on other speakers. Note that you may have to remove the output transformer to do this. Good luck with it.

Ed