He's not even TRYING to fix tube radios, and his repairs so far have been pretty entry level - soldering loose wires based on photos online, cleaning dirty contacts, and the like. But he's learning all kinds of stuff and he has to do a lot of experimenting with each radio to figure out where to patch in the Bluetooth wires so that the music coming from that can still be controlled with the volume knob, etc. so he's constantly learning more.
It's interesting to see the guts of these things. It's funny to me to see how most knobs control things with basically strings wound around them. It all looks so fragile and delicate to me, after spending all this time with steel gears and such in my machines.