The main areas to check for issues are the print head, the white rubber rollers, the brass knurled roller, and the tamp face.

In the first image you can see the area to inspect and clean on the print head. A dirty or damaged print head can cause smudges, smears, and/or lines to appear on the printed label.

Next to check are the rollers. Labels can wrap around the rollers, not allowing them to grip the label stock and can cause feeding issues. Check for labels stuck on rollers and for damaged rollers every time you clean the print head.

There is a special roller that is a knurled brass roller that grips the label backing and keeps it tight to allow the peeler to function. This can also get labels/residue on it and it cannot grip. Be sure to inspect and clean if necessary.

The tamp face must be kept clean and dry to allow the labels to slide onto it correctly. It needs to be inspected and cleaned often.