[electroking]

Intermittent short in the variable capacitor is likely. By the way, the following trick
will let you know if the local oscillator is working (assuming you have a
superheterodyne radio).

Set a good working AM radio to a quiet spot near the top of the frequency range.
Bring the radio to be tested close to the working radio. Now slowly rotate the
tuning knob of the radio under test. As you pass the point where the local
oscillator is running at the frequency of the working radio, you will hear some
kind of interference. For instance, if the radio under test has an intermediate
frequency of 455 kHz, and the working radio is set to 1400 kHz, the radio
under test will oscillate at the latter frequency when tuned to 945 kHz.
Good luck.