[mactec54]

I just check z axis move exactly 25mm up and down from start to finish. So steps of motor is correct.

Do I need to check backslash too ?

If the movement went down 25mm and it moved back up 25mm then your backlash would be ok.

After you had cut the parts where the Z axis had moved down more than it should, when the program finished did it return to the Z axis 0.00 position where it started