Hi Larry -
When you click the DFU menu button, you get the next menu with 2 items:
Reset and Enter DFU and Cancel.
OK, I never dared press DFU
and anyway added a slide switch for hard DFU,
too often required for hangs..
The full word:. Calibration is a switch that can be inverted text
to show calibration is being applied,
or normal text to show calibration is not being applied.?
OK, I see "CORRECTION", not "Calibration"
How often do you turn it on or off?
Maybe raw data helps understanding impact of shielding and layout changes?
Oristo