Interesting, no vault drop. The drives are actually 3M860.

I tried to set the current up - no change. Ive then ensure all the bits are well lubricated (the pump hasnt been run for a while), no real improvement.

Set the max speed down, seems OK at 700 although it should be able to do 2000 I think from the spec / manual.

Perhaps the lubrication is not getting to the dovetail / sliding area, difficult to get there without removing a lot of stuff. That said, it should be adjustable, will do some further research, perhaps the motors are stalling due to this.