Hmmmm. Didn't ask why he wanted to know which ones are the audio tubes......
If all three of them are good, and you STILL have no audio, this is the place to look next, for a burned resistor. It's supposed to have two orange bands, a red, then silver.
If this one is burned, your mode selector switch has broken down. That's the AM/USB/LSB selector switch.
Rare to find one that hasn't. One of the first results is R51 burning up. Attempts to use a larger resistor don't fix the missing audio.
It's also common to see the meter peg violently to the right when the meter switch is set to "Mod", soon as you key it, or maybe while receiving, both.
Of course, if you click it back away from "Mod" fast enough, the meter will survive. If you're too slow, "POOF", no more meter coil.
The replacement switch is expensive. And the labor to put it in won't be cheap, no matter who does it.
73
