I am well, thank you. I trust you and yours?
When to bias? There are four occasions:
1) When the amps starts to sound dark.
2) Sound stage starts to collapse.
3) Replacing, or moving the position of any output tube.
4) Tube issues. Sparks, crackling, red plating, etc... This includes low or no volume in one channel.
1 and 2 pretty much go together. I do not know how robust your NOS tubes are, but red plating is bad news for current production tubes in a SE40. My fast and dirty bias instructions go like this: Before powering the amp, rotate the bias pots all the way clockwise. After powering up the amp, allow at least 3 minutes for warm up. You will begin the bias process rotating the pots counter-clockwise as necessary for increased bias and vice-versa. Bias 610-615mV. Only allow a seven minute window of adjustment. If the unit is on longer than 10 minutes collectively, shut it off until cool to the touch (about 30 mins.). Try again. Ignore the first sentence if you are not replacing tubes.
This is the bias recommendation on page 3 of my SE40SCX kit instructions: Before powering the amp the first time after modification, rotate the bias pots all the way clockwise. After powering up the amp, allow at least 3 minutes for warm up. You will begin the bias process rotating the pots counter-clockwise as necessary for increased bias and vice-versa. The main thing you are looking for in biasing this amp is that the tubes never exceed 640mV. Notice if you start the amp from cold and monitor the tubes one at a time every ten seconds or so for the first 15 minutes (90 measurements), that the tubes climb to a peak and then settle out. They may peak once or twice, but they should be biased low enough (610-625mV is not uncommon) that they never exceed 640mV. This is a real pain, but it is the best way. If the bias exceeds 640mVs on a tube rotate the pot a bit clockwise, and start again with a cold amp. Continue if necessary. The ground wire in the bias harness is the wire furthest to the Left as it plugs into the board with the amp upside down, and the front facing you. The pot closest to the front panel on the side of the amp which you are adjusting will correspond to the wire closest to the ground wire in the harness. Next wire out......next pot out. Last wire in the harness....pot closest to the back of the amp.