[glyphmon]

Mike,

Without a tester, the best I can do is to swap the tubes for a known good one which I am willing to order.  I will try to disconnect the screen grid on the 6A8 tonight to see if that makes a difference on reception as Rod has suggested.  I am tempted to order two since swapping in the 6A8 from my 37-620 did not make the problem go away.

Is a short on the screen grid of 6A8 a common failure?  It would seem odd otherwise that I would just so happen to have two that exhibit this problem.  I will double-check also that swapping just the 6A8 or just the 6K7 does not impact the results.

Best wishes,
Roy