XY-Calibration global vs. local


Hello everybody,

recently we got some issues with our refurbished Form2.
we are using a scaling print (see picture below) to measure and calibrate the scaling of the printjob.

we are using the “Fine Tuning” option for the calibration.
Recently we can’t calibrate good enough across the build area.
The 4 cubes, for example, have in cured state (grey) a x-dimension of 19.82 mm / 20.03 mm / 19.87 mm / 20.01 mm. So in the same print, there is a cube with -0.9% x-dimension (rel. to 20 mm / stl-file) and also one with +0.2%. Since we use the printed parts as a master form, this variance is critical for us.
The XY-calibration of the previous Form2 showed better and uniform results (19.99 mm / 20.01 mm / 20.00 mm / 19.99 mm).

So the question is, is the scaling variance across the build area usually as bad as we got right now?
Can it correlate with the refurbishing process of the second printer?
Did anybody experienced similar situation with his printer?

Thanks for your help

Best regards