For any wire measuring system, the serial number is not on label but on display. Please turn on the device and read the displayed number.
Check that the paper is well fixed and the nut is screwed in the right sense. If everything is correct, the battery might be down. In this case, replace it by pulling out the mechanism. Battery is placed behind the chart under the mechanism.
Adjustment is forbidden for any recorder compliant with EN 12830 norm.