POP3 calibration issues

Noticed a degradation in the accuracy of my new POP3 yesterday ( details in another post POP3 accuracy degraded ) I tried to re-calibrate it today and found some issues at the step depicted in this video : https://www.youtube.com/watch?v=KteydtF-CS4

I used to be able to keep the ball in the pitch and roll adjustment bar on the screen at around the middle and shift the scanner horizontally to make the white and red circle coincide. However, at this particular orientation of the board, I had to roll the scanner to one side ( right side lower ) before I can make it happen. This can be seen from the roll indicator as well as the fact that the calibration board is shifted to the right side of the camera’s view. I don’t remember encountering this in the first calibration.

This issue is not seen at any other orientations of the calibration board such as this one : https://www.youtube.com/watch?v=CBfztMSDDkw

Is there some problems with the scanner ?

No it is nothing to do with your scanner , it sometimes jumps . I would suggest first you adjust the distance then move to the center .

Best way is to keep your elbows on your knee or table for support . Make sure there is good lighting in the environment .

Calibration is not really a smooth process , sometimes you need to do it twice if errors happens like shaking of the camera .