1. When the printing is blurry, please adjust the print density and try again.
Example video of adjusting printing quality for M220. https://www.youtube.com/watch?v=fVteTKY6yYA

2. Clean the print head, especially the black line, with an alcohol swab to ensure there is no dirt on it.

3. Please try using another roll of paper for printing. The current one may have been affected by moisture, which can impact the print quality.

4. The following SN can be upgraded to the corresponding firmware to solve the problem of unclear printing of small characters.
M221：Q218 V1.0.3 M220：Q198 V1.0.2 M200：Q197 V1.0.5