Just wanted to revisit this, and post my lessons learned. I fixed my problem, and it was a two part problem.
Problem 1: When grounding the shield on my servo power cables, I made a pigtail, spliced them to a green wire, and ran those about 24 inches away. The right way was to ground them on the drive itself, along with the ground wire from the servo. This was causing noise to spew everywhere!
Problem 2: I made a wire harness, to allow my mpg to enter the cabinet using a cannon plug. Inside the cabinet, I used two cables from the cannon plug-jack. One to a galil axis, and the other to I/O stuff. These are all shielded cables, and I chose to ground the I/O cable shield inside the cabinet to avoid ground loop, leaving the Axis cable shield disconnected from the cannon plug-jack. Oops. The fix was to remove my shield ground from the I/O cable, and to ground all of these shields to the galil axis cable.
Man, the time I wasted thinking about resistors, capacitors, you name it.
I also realized that I should be using twisted-pair cables for my extension cable. Hopefully, the shield will prove to be enough.
Thank you all for the help, I am almost there!
Rob