Try the following if your Fargo DTC400 is failing the ribbon sensor calibration:
Try a different USB port on your computer
Try the calibration on a different computer
Update your printer driver and firmware to the latest on Fargo’s website and try the calibration again
Contact a Fargo Authorized Repair Center as the ribbon sensor, power board, or main board will need to be replaced
dtc400 will not calibrate changed senors main logic and power interface board
Is the firmware updated to 4.3.0.1? Have you tried to calibrate the printer on a different computer? If you replaced the lower sensor (Part# A000374) it may be out of alignment. Please remove and reseat it and try the calibration again.