I run a Busellato Jet3000 3 axis running Genesis software

I have been having a Z axis servo error come up and also says Z axis cannot finish movement.

I have had two engineers look at it, one was an SCM engineer who is very skilled with these machines and neither can find the fault so asking on here if anyone has any other thoughts on this.

We have tried three Z axis motors
three different cards
replaced encoder cable
replaced power cable
replaced relay for the brake
swapped Y and Z wires over on the cards and tried moving manually and still the same
tried all 4 different combinations of swapping the 3 phase wires around (3 wires)

We are stumped!!!!!!

Any ideas of anything else we can test or try will be greatly appreciated

Many thanks