I really like this old radio....

I know where you're coming from. I've picked up a few of those old
multiband radios at yard sales and from trash piles. They're a lot of
fun to play with.

Unfortunately, the only way you'll find parts for them, particular the
pushbutton band selector switch, is to scavenge them from another
radio.

The volume control is probably a stock part from Radio Shack, Mouser,
MCM, or any of the usual suspects. They're generally about 5K or 10K
ohms, with or without a on-off switch as well. I had to replace the
volume control on my first shortwave radio, a small multiband affair.
It is a Peerless model 1444 14 transistor, 4 band radio. I modded it a
little. The replacement volume control came from Radio Shack. My
control really was broken, beyond any improvment that contact cleaner
could provide.

The radio needs a new dial cord. One of these days, I do believe I'll
replace that dial cord too.