Zebra ZD421 skipping labels: calibrate the media sensor

Steps

1. Open the printer and check that the roll turns freely on its holders and the labels feed straight under the guides, then close the lid fully.
2. Check that the movable media sensor sits under the gaps between labels; a sensor left to one side is a common cause of skipping on this model.
3. Run the printer’s SmartCal: with the printer ready, hold FEED and CANCEL together for about two seconds. The printer feeds a few labels and stops. Confirm the sequence in the printer’s guide if the lights behave differently.
4. Print one test label.
5. If it still skips, check that the printer’s media type matches the roll: labels with gaps, continuous media, or black-mark media.
6. After changing the media type, calibrate again and print one more test label.

Why a printer skips labels

The printer finds the start of each label with a media sensor. After a roll change, or a change to a different kind of roll, its last measurement no longer fits the labels, so it feeds past them and prints a blank or half a label.

When calibration does not fix it

• Clean the media sensor and the label path, following Zebra’s instructions for the model.
• Try a different roll to rule out a damaged liner or uneven gaps.