fixing am radio?
I fixed a 1966 Dart radio by replacing the output transistor that is on the heat sink.
First make sure it has power and antenna. An amplifier can be attached to the volume control pot to bypass the amp and see if the front end is working.
Study up on superhet design, they have RF, local oscillator, IF, detector and AF sections. The two RF, signals are viewed at the tuning capacitor, the IF at the 455kHz transformers and audio at the pot and speaker.
It is not too hard, I started at age 7 and have never stopped working with electronics.