Well, after doing nothing more really than my regular monthly service a week
or so early I have dry air again. I ran the air dryer for about 8 hrs
yesterday with zero moisture build up in any of the downstream separators.
I used it simultaneously for two mills with air seal high speed spindles and
assorted other air tools while putting the output shaft and wheel spindle
back together on the front axle of my little 3320 tractor.

I guess the system was just really wet, and needed to be dried out slowly
and tediously.

I think I am still going to add desiccant driers after the separators at the
machines as a second line of defense.