[Texasrocker]

Most of the "gurgly" underwater type sounds Ive experienced in the past,in a fully restored set, were a improperly grounded loop-antenna back to chassis. Some loop antennas were the "balanced" types,some 3 or 4 wires type "coil-tapped type"antenna, that the orig mica caps & resistors were previously removed that connected center of the loop antenna back to chassis ground by a previous hacker. Try adding a 250 pf cap, or similar, in series with about a 150k resistor ( if I remember correctly?) from center of loop antenna back to chassis. Play around subbing in/out different values mica caps/resistors combinations from the center antenna loop lead back to chassis in series. If you know your resistors/& tubes are all within spec, this antenna solution idea may help. Ive been lucky before finding antenna probs by looking closely over the schematics, and finding some orig antenna loop parts/components missing in many restorations of the past. If we are all discussing overall audio "distortion"?.. try subbing other known-good output tubes as subs also. Sometimes,.. the IFs trans can be tweeked abit to "hot" also when aligning by ear. If so, back'em off abit and detune volume down slightly.Ive also ran across orig cold-solder joints at the IF cans wiring-points. Add abit of new solder just in case. Just submitting a few other ideas to check.