So...by "accident", a.k.a. unintentional experiment, I learned:
My GQF 1402 can easily be pushed to excessive humidity as evidenced by condensation on the door.
Humidity and temperature are very strongly interrelated; you cannot stabilize temps until humidity is stable, and vice-versa. But once the temp is set and the humidity is stable, the incubator is rock solid.
If you set a very fresh egg with a tiny air cell and maintain moderately high humidity per GQF instructions, the air cells will go away completely.
Eggs with no air cells do not develop embryos.
Of the 30 eggs I set for my customer, only 8 show any development. They are 13 days in so the blastodisc is no longer viewable, but there are no blood rings, and those with no air cells showing when candled are completely clear. I'll scramble them up for the birds tomorrow and get a better look inside. More than half of the viable eggs are from my young EEs.
I am going to start my next incubation of fresh eggs dry for the first several days and see if the results are any different. Since the number of viables is so low, I offered to set her a dozen more for free.