[k9uw]

1. Check continuity of the output (secondary) of the transformer 46 (audio diving the grids of 42 tubes).
2. Check the primary of the audio output transformer.
3. Have you checked all your tubes? Check the 42s for being good.
4. Check their plate voltages.

Thank you, morzh!

I will pursue your suggestions and report back. As you know, this radio has three 42's and I know one of them is weak. Moving the weak one between the three locations did not seem to matter but I'll pay more attention and try it again.