POP3 accuracy degraded

Have been playing with my new POP3 for about a week. Initially the accuracy was very impressive, at good/excellent distance range, the error in the scanned thickness of a piece of wood board was around 0.06 mm , today I found that it has degraded to about 0.14 mm and the magnitude of the error is very consistent. Error of this magnitude is not too bad but enough to make me unhappy … The set up is exactly the same as before - A piece of wood board next to the stock bust ( for feature tracking ) on the stock turn table. I have updated the firmware of the scanner and re-calibrated it N times but still the error is consistently 0.14 mm. It seems that it has settled at this error for good. That leaves me wonder what has happened. I have not dropped it or done anything bad. What can I try to restore the original accuracy ?

Keep the distance at Excellent/too near rather at Excellent/ Good

From what I see in the preview you should proper re calibrate the POP3 with the board , it is too noisy , it should be more smoother .