Once I got the radio home I unscrewed the back and the chassis and slid the metal base out of the case.  I also found the schematic online and installed a modern electrolytic capacitor into the chassis in parallel with the old one.  Although not period correct, the mod is hidden and should not detract much from the vintage electronics.  This repair fixed the loud hum.

The radio is shown above.  The left knob is the power/volume control, the middle is the tuner mechanism and the right toggle switch for tone control (treble cut or normal).  The radio is available in various cases per the manual, and I presume the same chassis (or variant) would be used making this the common aspect for this line of radios.  Available cases were Walnut (this one), Blonde Wood, Mahogany, Brown Plastic and Ivory Plastic.

Being an AM radio, the sound loudness and quality is highly affected by the signal strength and the orientation of the antenna loop to the radio tower.  You will be able to hear clicks and pops from nearby electrical appliances turning on and off, and thunder storms will sound like crashes.  Incidentally, I thought of building a lightning detector some years ago by using a small AM transistor radio set to an unused channel.  The loudness of the crash sounds would tell you how close or intense the lightning is.