The printer detects the TOF (top of form) buy passing light through the label backing. If a label is present there will be a different light
resistance than when there is just the backing present. Main causes of this error are incorrect position of sensor or debris stuck in the sensor. Refer to the users guide for positioning the sensor correctly. If the label
is of the gap type, the sensor should be positioned so that is is in the centre of the label. If the labels are of the black mark or cut-out type the sensor hole should be positioned over the cut-out or black mark (the black mark should be carbon based and not glossy).
The other cause of this message is debris stuck in the gap sensor causing the printer to not be able to see the label gap. On most printers cleaning of this sensor requires the covers to be removed and the sensor extracted from inside the printer (refer to service guide). DO NOT USE SOLVENTS TO CLEAN THE SENSOR
Ribbon not advancing or incorrectly installed
Incorrect installation of the ribbon will cause this error. Please refer to the users guide on installing the ribbon. Make sure it is not passing through the label gap sensor also.
Make sure the ribbon switch is not on if there is no ribbon installed.
When then the feed button is pressed make sure the ribbon advances at the same rate at the label. If it does not the most probable cause is a dry spring inside the printer. Remove the main cover and lubricate the spring.
Label size sent to printer is too large/small
Some label design software can send label dimentions to the printer if these are incorrect the label/ribbon light may appear. Check label fromat in the software is correct.
Incorrect media loaded
If incorrect media is loaded the error light may show, this is because the gap sensor may be setup to read black mark instead on gap etc. Change media type in software or on printer.