hello everyone..

I am working on a Bridgeport 760/22, TNC 370 control.
Previously parameters of the machine were lost, we reloaded the parameters of the machine.
Now machine is running okay but Z-Axis is giving size variations.
This is picture of component....Attachment 190922

The cut depth changes 150-200 micron after 2-3 components, we again reference the machine and size returns to okay.
Now is it parameter problem because parameters are reloaded or some mechanical problem?

We have checked the coupling and chuck nut of Z-Axis and tightened properly.
Set the backlash parameter of Z-Axis.
Now what could be the problem please help here...