I find that writing a status note often leads to me solving the problem
but not this time...
Easiest things first. Swapped in a spare 24 PSU, no change. X still
stalls at any useful speed.
The wiring between the Geckos and the steppers are the same for X and Y,
so I swapped the X and Y steppers on the motherboard to see if it was a
Gecko or a motor. But now it works, X moves along just fine for a
several minute test. Things are on the wrong axis, so cutting anything
wider on X than on Y isn't going to work. Reverted to the correct
installation and X goes back to failing under speed.
If X isn't getting enough power then how could swapping the steppers to
the mother board make any difference? Y is a much larger motor than X,
1.4Nm (2.8A) vs. .4Nm (1.5A). So if X is stalling because it is not
getting enough power from the X Gecko, how could the X Gecko drive the
larger Y motor?
Maybe there's a problem with the Geckos or one is loose? Swapped the X
and Y Geckos. No improvement.
I'm really kinda stumped at this point.