How do I make use of the preset buttons? Pushing them does absolutely nothing. The attached images show what the presets look like on the chassis (they're old pics prior to cleaning and recapping).

On a related note, the knob that chooses the audio source has 4 positions. I know that 3 are AM, shortwave, and the turntable. What would the 4th be?

The fourth is for the pushbuttons. They will have to be set up for stations in your area. Read the instructions for doing so adjacent to the schematic on NostalgiaAir.

http://www.nostalgiaair.org/Resources/233/M0024233.htm

That's perfect. Thanks!!!