Thank you for posting on the HP Support Community.
Don't worry as I'll be glad to help, I have a few troubleshooting steps we could try to fix the issue:
Use the link to complete the below-mentioned steps: https://support.hp.com/in-en/product/hp-officejet-pro-6960-all-in-one-printer-series/8289579/document/c05076934
Step 2: Clean the printhead
Step 7: Check the estimated ink levels
Step 9: Make sure the ink cartridges are properly vented and seated correctly
Step 10: Print a Print Quality Diagnostic Page
Step 15: Clean the printhead
Step 16: Print another Print Quality Diagnostic Page
Hope this helps! Keep me posted for further assistance.
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