[Terry Judkins]

Replace ALL of the paper capacitors would be my take on the matter. Then troubleshoot. But you can pull the first audio tube and see if the popping continues. If not, the trouble is in the RF/IF stages or detector. If it continues it is in the audio circuits. Bad leaky caps will/can cause the snapping symptom. Tubes are usually good in thease old radios although it is possible to have a bad one cause your symptom.