Steve, Good to hear it survived the cross country trip including bouncing around in the rental car’s trunk. You would have to add an antenna wire to the screw in the back if you want better reception. It should be re-capped at some point anyway as it looks quite original. Have fun with it. The switch had me baffled as well. There seems to be a shielded cable and a pack of capacitors alongside the switch.
The modification looks as old as the radio itself.
