[Hallicrafters] SX-28A Issues

[Waldo Magnuson]

Hi,  My SX-28A was playing okay (after a long rest). Then the BCB station went away and the audio became a loud hum. I've tried: pulling the 1st audio amplifier (v12, 6SC7), hum remains, Substituted both 6V6GT audio output tubes - hum still present, paralleled C48 & C49 (power supply output caps) and C47 (cathode bypass for 6V6s) - no change, B+ measures maybe 150v (not schematic 250v).  Any suggestions welcome.
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