If your printer prints blurry or with a white line, it is most likely because dirt has gotten onto the thermal print head inside the printer.
To fix this, open the printer where the label roll is placed.
Take a cloth with a small amount of alcohol (or cleaning alcohol) and wipe just under the serrated “knife” where the labels come out. Under that area is the thermal print head, which most likely has some dirt on it.
Try this first. If it still does not work, you are very welcome to email us with pictures, and we will help you find a solution.