After updating the Prism III firmware from 6.007 or lower to 6.008 or higher, the Ribbon Sensor must be calibrated. Follow the procedure below to calibrate the sensor. 

1. Remove the ink ribbon from the printer.
2. Press and hold the printer operator button as if resetting the ribbon (6 - 8 seconds).
3. When the printer tray pauses partially open, release the button, then quickly press and release it twice.
4. The printer emits a high pitched beep to indicate that the ribbon sensor calibration completed successfully.

Note: The printer will continue to operate if the ribbon sensor is not calibrated, however, the green power LED will flash rapidly and the printer may encounter ribbon detection issues.