I slowed it down , I sped it up, I changed number of steps and retuned the motor went through complete set up again. And again it was off on every rotation and it was never linear sometimes it was a lot and sometimes it was very little but it was always off and it didn't matter whether you were going forwards or backwards.
I took the leads from my A axis driver, and connected it to the tool changer stepper motor. Now it works fine so it must have been the driver. Everything was working fine and then this driver just died. Glad I was watching it cut when it went to do the tool change or it would have been a terrible crash.
Need to figure out a way to make a closed loop system, that's affordable, for steppers that work with mach3 so those of us with older systems can upgrade them and keep them running without having to spend a fortune on new software and Hardware.
So now I need to buy a new driver so my rotary table can be back up and running on the mill.
Thanks for the suggestions
David