[TNTrawlerman]

Thanks Richard,
I have tried another speaker (4 ohm) and it does not seem to make any difference. When the volume is low, the sound seems to be pretty well clear, so that leads me to believe that the problem is after the volume control. That leaves the 1H5G detector/pre-amp circuit and/or the 1A5G final output circuits as one or the other of the "culprits". Reading the specs for the 1A5G tube, it seems that it wants a 25,000 ohm impedance. I temporarily removed the output transformer and injected 0.1 volts @ 1000Hz into the speaker side secondary, and measured the primary/secondary ratio, then squared the ratio and multiplied by 4 (speaker impedance) and the result only came out as about 4800 ohms impedance. It looks like the output transformer is original, but hard to tell for sure. I just wondered if anyone had run into the situation where the wrong reflected impedance had caused this kind of "gargling" effect to the sound at any volume. Also, while I realize that the 1A5G tube can only output about 100 milliwatts, the volume at max seems very "puny" to me. Any thoughts from anyone are appreciated.