Ed, that is a very nice (and unusual) radio. interesting the way the chassis is assembled on the black panel.
I have no idea what the knobs did look like having never seen one.
I have a collection of knobs, they aren’t well organized and the problem is if you mix them all up finding two the same is a challenge, but figuring out which were inners and which were just normal knobs is a challenge never mind putting the set of 4 together. a lot of these older sets had either rubber or black bakalite knobs but some were wood. I make no promises but I’ll make a mental note that next time I am going through them to look for any outer knobs that look very old. hopefully someone will chime in with more info. Nice restoration. I guess the switches were a power saving feature for battery life. They were going green and didn’t know it.
I have been trying to piece together and AK12 breadboard and it had such a feature to listen with headphones or to run a speaker.