Step 1 ![](https://publications.lexmark.com/media/ids_assets/images/transparent.png) Check if the printer is using a genuine and supported Lexmark toner cartridge. Note: If the toner cartridge is not supported, then install a supported one. ![](https://publications.lexmark.com/media/ids_assets/images/transparent.png) Print the document.
Do vertical dark lines or streaks appear on prints? | Go to step 2. | The problem is solved. |
Step 2 ![](https://publications.lexmark.com/media/ids_assets/images/transparent.png) Remove, and then reinstall the imaging unit. Warning—Potential Damage: Do not expose the imaging unit to direct light for more than 10 minutes. Extended exposure to light can cause print quality problems. Warning—Potential Damage: Do not touch the photoconductor drum under the imaging unit. Doing so may affect the quality of future print jobs. ![](https://publications.lexmark.com/media/ids_assets/images/transparent.png) Print the document.
Do vertical dark lines or streaks appear on prints? | Go to step 3. | The problem is solved. |
Step 3 ![](https://publications.lexmark.com/media/ids_assets/images/transparent.png) Replace the imaging unit. ![](https://publications.lexmark.com/media/ids_assets/images/transparent.png) Print the document.
Do vertical dark lines or streaks appear on prints? | Contact customer support. | The problem is solved. |