If the SC30 does not read the marks occasionally or not at all, the cable could be defect. To change the cable, please follow these instructions:
1. Please remove the screws marked with the red arrows, uninstall the cable carefully:
2. Remove the right side panel ( 6 screws ) the main PCB appears. Uninstall the cable from the PCB and remove the defect cable out of the SC30:
3. Install the new cable, lead it the same way it was installed. Please make sure that on both connections, the blue strip at the cable is visible to you