Having nevar worked with the Mitutoyo scales, I can't give a definitive answer. But I have worked with many "Strain Gage" scales over the years. On the scales I have worked with, the "flexible" bar can be extended or shortened but a change in length will effect a change in calibration. In that, if you shorten the bar, the scales will read light.
The theory of operation is a resistor bridge attached to the flexible bar. As the bar flexes, the resistance will change. Changing the bar will change how the flexure effects the resistor, hence requiring re-calibration. Such strain gages can be re-calibrated, but for an integrated system, you would need to contact the manufacturer for details on how to accomplish it.
Afterthought: I may well be mistaken as to what you are describing. It may be a linear measuring device, not a scale as such. If that is the case, my description is "out in left field" and has no bearing on the question.
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