Remove the cam lock arm spring from the left side of the carriage.

Extension spring, OD 0.123", WD 0.014", compressed length 0.34"

This spring pulls the arms against cams fixed to the digit shafts so that the digit shafts will not rotate when the zero-setting mechanism is not operating. It is important that the digit shafts themselves not rotate, since each digit wheel needs to be able to rotate freely on the shaft.