Awesome restoration product...nice job..and Interesting about it's magnet setup ... is the field coil fed with 6 volts DC from the Plymouth's battery to magnetize the center pole?..., or is the field coil doing double-duty, serving as the radio's B+ power supply choke and speaker-magnetizer?
...or... is the field coil and it's center pole the actual "primary" of the radio's push-pull audio output stage "transformer", and the class A idling current that flows through the two output tubes is what magnetizes the center pole and the voice-coil's audio variations of the station being listened to opposes or attracts to the center pole?.... if, so, how very interesting!... and would definitely require a special jig to test it with, or the radio itself... I'm intrigued by that speaker :-)
Unfortunately Terry, I can't really answer your question as I am not into electronics. I have a great amp repair guy who does all that. facebook.com/search/top/?q=desert%20amplifier%20repair. I'm sure I could ask him. I can tell you however that this same type of speaker is used in many antique juke boxes and I've done a number of repairs on those. I have never been able to gain access to a push pull style amp for testing but luckily my repairs on these type speakers has always been successful.......so far.
The point isn't to show you how to do the repair, there are plenty of "How To" videos for that and I'm not in the habit of teaching people "How To" avoid doing business with me. I'm showing that I can do this service for those who need it as so stated in the last couple of spoken lines. Now, I kind of doubt you have a 1939 Plymouth in need of speaker repair, but even if you did the video shows this type of speaker can be repaired to keep the car original, however, most likely, not by the average person as there are no model numbers or parts listings for such a speaker. You can't just call upon your local auto parts dealer and say "Give me a speaker rebuild kit for a '39 Plymouth". Such kits do not exist. Only a skilled professional would have the tools, knowledge and resources to determine and find the correct parts. And only a few shops in this country would even bother with such a job. Thanks for your comment, have a nice day.
