DIAGNOSIS The label roll core is binding on the spindle or the paper guide arms are set too tight, causing drag.
FIX Power off and open the lid. Remove the label roll. Inspect the black plastic spindle for cracks. Manually rotate it; it should spin freely. Re-insert the label roll. Ensure the two blue paper guide arms are adjusted so they just touch the sides of the roll, with 1-2mm of play. Do not clamp them tight. The label should peel from the top-front of the roll, not the bottom. Close the lid firmly until it clicks.
IF THAT DIDN'T WORK The feed mechanism is misaligned due to a previous paper jam. With the printer off, manually rotate the silver platen roller (the rubber roller) several full revolutions in both directions to re-seat the gears. Check for a small fragment of torn label stuck in the label peel bar.
HEADS UP Never use 3rd party label rolls with a core inner diameter less than 1 inch. Smaller cores create excessive tension and strain the feed motor.