My guess is probably some bent plates on the main tuning capacitor. I
wouldn't bet the farm on it, but at least the barn. It would be really
easy to check by just doing a continuity check between the stator and
the rotor. You might even feel some resistance in the tuning knob when
you hit the noisey section. With a little care you can bend the
offending plates back into position. Have an old RCA AA5 that still
works to this day after my Elmer showed me how to fix it 25 years ago.
Cheers. de W8IJG