OfficeJet Pro 6970 prints curvy black lines

[HajoH]

Hello, my HP OfficeJet Pro 6970 is printing a handful of curvy black lines on every printout (also on the test and diagnostic pages) for some time now. All tests/cleaning programmes have been run. After a lengthy chat, HP support sent me a new black cartridge, which I installed (I am an InstantInk customer). Unfortunately, no improvement. Does anyone else have any ideas? I have not yet found a plausible solution here in the community.

[Hawks_Eye]

Hi @HajoH 

Welcome to the HP Support Community!

Thanks for posting your query! We're here to help you get back up and running.

Since you've already tried cleaning programs and replaced the black cartridge without improvement, the issue likely stems from printhead clogging, roller contamination, or internal hardware misalignment. 

Here are some additional steps to try:

1. Perform a Deeper Printhead Cleaning

• If you've only run automatic printhead cleaning, try a manual clean:
  • Remove the printhead (if detachable) and gently clean the nozzles with a lint-free cloth and distilled water.
  • Let it dry completely before reinserting.

 

2. Inspect & Clean the Rollers

• Sometimes, contaminated rollers cause streaks or irregular patterns:
  • Open the rear access panel.
  • Wipe rollers with a dry lint-free cloth.
  • If ink buildup is visible, lightly dampen the cloth with water only (no alcohol).

 

3. Adjust Paper Settings & Try Different Paper

• Ensure the correct paper type is selected in HP Printer Settings.
• Test with a new high-quality inkjet paper—sometimes coated papers cause ink pooling.

 

4. Check for Internal Hardware Alignment Issues

• Run a Print Quality Diagnostic Page (HP Smart → Printer Maintenance).
• If alignment errors appear, perform a printhead alignment.

 

5. Update the firmware on an HP printer

• HP regularly releases new firmware versions for printer enhancements, app updates, or issue fixes. Update the firmware regularly to get the most out of your printer.
• Click on the link below for instructions on how to update the firmware of your printer.
  https://support.hp.com/in-en/document/ish_1776648-1643972-16

 

6. Run the "Paper Feed Cleaning" Utility

• If available in HP Printer Tools, use this option to clear debris in the feed path.

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Take care, and have an amazing day!

Regards, 

Hawks_Eye