[morzh]

So, we can safely exclude

1. the antenna coil (was not involved in the failure of the 2nd test).
2. the 1st IF can (the signal was going through it during he 1st test).
3. Tuning cap and its trimmer (same as in the #1, were not part of the failure).
4. AVC circuitry including the 6H6 (the voltage was good during the 1st test and did not drop)
5. IF amp, the 6K7 and the 2nd IF can.

The items left are:

1. 6A8 itself (you said you changed it, right?)
2. The oscillator circuitry (oscillator seemed to work but the whole mixer part is under suspicion as the failure involves the 6A8 being part of the signal path).
3. The oscillator's (the right side) of the band switch.
4. R1, C4, C1, possibly C6. R1 especially.
5. Any solder joint involved.






When you say your B+ is low, was it the same during the 1st test (where all was good?)

PS. For the heck of it, can you do the Test #2, and measure the Candohm's voltages (relative to GND, all three taps) when you start and repeat when it craps out?