Called AMC and as always, talked to a great guy.

Just wanted to post this summary so as to make it available to anyone
looking for same.

Pot 1, Loop Gain, is the one responsible for responsiveness of the
motor to error in commanded parameter (speed in my case, as I run in
velocity mode). To adjust it, turn it clockwise until the motor starts
vibrating when commanded zero. Then back out 1-2 turns. Gunner pretty
much said the same thing.

Pot 3, Reference Gain, has nothing to do with stability of the servo
system and represents only the proportion of how much speed you get
for a given volts input. Fully clockwise it means 100% available
speed.

I will make some adjustments tonight based on that, so as to get a
stable system operating at top performance. During tuning, I turned
down Ref gain, for no good reason as it turns out. So my motors do not
operate at top speed avaliable from the drive.

i