If it is printing only the front of the card, then ejecting normally:
- check all of your settings in the driver, as well as your card-printing software, specifically those that specify single- or dual-sided (duplex) printing. Make sure they're set for 2-sided printing.
- Also check that you specifying printing both front-side and back-side of the card, etc
- Make sure your card design is for a 2-sided card.
If the card enters the flipper, but gets stuck (doesn't flip), and does not eject, then you may have a fault with the flipper module itself. There is a diagnostic program freely available (the Fargo Workbench Utility) directly from the manufacturer's website at www.hidglobal.com. Download and install it on your PC. It includes a printer information section that can calibrate sensors, film, etc., and also can send direct commands to the flipper to level itself ("home the flipper table"), as well as step it in either direction.
If you have an issue that is not addressed by these built-in calibrations and other tests, then your unit may need service from an authorized repair facility, like Safe-Card ID Services.