Noisy Servolite CNC hardware

Gents,

I was thinking that a problem I've had since 2000 when I put my CNC
together, could maybe get resolved with your help.

I am using Mr. Bill's Servolite CNC hardware to drive my 3 Ametek
servo motors at 75 volts. I think Mr. BIll's hardware may have
pre-dated the Gecko drives. Dan Mauch may remember.

The problem is that when I first had everything running back then,
there was a lot of jittering in the motors. The 75v pwm cables are
separate from the encoder cables. So 2 cables go to each motor. I had
neatly bundled the 6 of them together and routed them out of the way.
Eventually I found that if the 6 cables were separated that the motors
were quieter. But I have them taped across the lower portion of my
rack mount cabinet. It's ugly and not a clean as I'd like.

I had each cable's shield grounded to the rack mount chassis, only at
the connector. When I removed the grounds at the connector it helped
significantly reduce the jitter.

Are there any fixes learned over the years for quieting down jittery
motors. I'd really like to route the wiring nicely. One of the guys
here in this group that also lives in San Jose put ferrite beads on
his cables and it helped. I only bought 3 ferrites, duh, but have 6
cables. So I need to get 3 more. Anyway, what else can I do to my
system to make it tolerate the cables being closer together?

Thanks!

Mike