[EdHolland]

OK, thanks

I am looking into various options, but those particular tag strips are very nice quality.

Yesterday I had another chance to poke about on the radio. The 11K section of the Candohm had mysteriously repaired itself (for how long?) so I disconnected the temporary resistor, and started measuring voltages. It was at this point I realised that the service sheet info I have is just plain wrong in this department. Looking at the 6F6, it called for -2.5 V on the control grid. The circuit was producing ~-22V, far more in agreement with the datasheet value given for a 300V HT operating point. This time, the radio stayed on, no intermittent problems. The sheet also calls 5V ac for all the filaments, which is just plain nonsense.
Other values around the radio seemed to make sense, and nothing was a cause for alarm. More testing this weekend while I wait for resistors and tag strip. I need to clean up the chassis and replace the dial before proceeding with alignment.