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Mike,

Full recap (excluding Mica) is done.
I do not have access to a tube tester.  Two tubes are new from Bob Dobush but neither of the 6A8 nor 6K7 were among the new ones.  I have attempted swapping from my 37-620 for its 6A8 and 6K7 and the test results are the same but admittedly have only tested those with both tubes in at the same time.  Though similarly "operable" I have no guarantee that the Philco's tubes are good either.

Rod,

So, completely desolder the connection for the screen grid on the 6A8?  I will try to do this test tonight.
Reception so far hasn't really been problematic, but I also don't have a great frame of reference.  There is only one nearby AM radio station which does come in a little and is understandable.  My AM transmitter comes in great.  And as before, I was able to tune into a Romanian station on shortwave.

In lieu of a tube tester, I'm not opposed to ordering a replacement 6A8, if that makes sense as a next diagnostic step.

Best wishes,
Roy