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[Electronic M]

Welcome. On an in person local level antique shops, flea markets, thrift stores, estate/garage sales, and the curb on garbage day if you are in an older neighborhood are the places to look. On line there is Craigslist, ebay, and a few other places.

I'd recommend that you get a copy of the Sam's photofact folder for one of your sets and poor over the schematic and component layout diagrams and learn what is what. I'd start with a tube table radio like an AM only AA5 and trace out it's wiring versus the schematic, then replace the electrolytic and paper capacitors...That will give you a good intro to reading schematics and soldering. Next I'd get a tube tester a multimeter, and an oscilloscope as starter test equipment.

That Truetone is a very rare bird. Odds are it uses an RCA based chassis as most makes that did not design their own color chassis used RCA designs. The ones who designed their own were Zenith, RCA, Admiral*, Magnavox*,GE, Setchell Carlson, and perhaps one or two more.
*after the mid-60's