Once the tubes are confirmed good, caps are changed, and all relevant adjustments have been tried my default is to check every resistor in the circuitry that is potentially related to the symptoms...In sets I really care about I may even go through the resistors in some sections before first power up.
Some sets will have most resistors out of tolerance while others will have almost none. I'm restoring a Sylvania in the rectangular tube section that seems to have nearly ALL resistors in any given section I go over in detail out side their specified tolerance.
