Hello, please confirm the following points:
1. Use industrial alcohol and cotton to clean the print head and roller, removing any dust.
2. Check the roller for any marks from cuts or scrapes that may cause unclear printing at a fixed 360-degree rotation position. Replace the roller (contact after-sales service for this).
3. Check if the print head is damaged at a fixed position and replace it with a new print head if necessary (contact after-sales service for this).
4. If the above steps have been confirmed and the issue persists, please contact after-sales service for repair.