Use the Sa command to adjust all the sensors in the same process:
Make sure a color ribbon is inside the printer, but remove the stack of cards.
In the Print center/Maintenance/Printer command prompting, send the Sa command (this is case-sensitive–capital ‘S’, lowercase ‘a’, no spaces):
The “warning-LED” from the control panel will flash.
Open the cover. The “warning-LED” will stop. When it’s on again, close the cover.
The “card/ribbon-LED” will flash. Insert a card in the feeder
The card will be fed, ejected then the sensors will be adjusted.
If this procedure has been followed too slowly, a “timeout” message may be displayed.