If you have a DFM, DMC, ComTouch or Centor digital displays remove the display. Send the display and any load cells to Com-Ten for calibration. Consult your operator's manual for removal instructions. For fastener testers the load cell assembly is removable. FG and CFG series load cells are also removable. It is recommended NOT to return the complete tester because of damage in shipment. Include a name and phone contact with the equipment.