HP X551DW Printhead/Ink Problem - Cleaning doesn't fix it

[gbuxton5]

Good afternoon HP Community - I'm hoping you can help me troubleshoot an issue with our HP Officejet Pro X551DW.  It's been working fine for months, but it now has vertical gaps (whole page) in both black and color ink when printing.  I have tried the various cleaning functions (multiple times) and looked online but can't find any suggestions.  I'm suspecting the print head itself is either broken or really badly clogged?

The printer is connected through direct USB to my computer, but the same problem also occurred over a network connection.

No error messages appear on the printer or computer.

When does this happen?

All B&W and color prints that go through the printer, both from a computer and from the printer itself (reports).

I have attached pictures of the print quality report, which show the changes with cleaning. 

Picture #1 is before any cleaning (had sat without printing for about a month)

Picture #2 is after a level 3 cleaning has completed.

Picture #3 is after a 2nd level 3 cleaning has completed about 4 hours after the first one has completed.

Picture #4 is about 4 hours after the 2nd level 3 cleaning completed

Picture #5 is after the 3rd level 3 cleaning is done (it looks as bad as the first one)

Solutions I have tried
All levels of cleaning (multiple times)

Print Smear utility

Firmware update

Factory reset to default firmware (after the firmware update, so actually have tried 3 levels of firmware)

Different ink cartridges (both genuine HP and 3rd party) - cartridges work fine in another printer (X576dw)

Any suggestions?  Help!!!!

[gbuxton5]

Bump - any assistance would be wonderful!

[gbuxton5]

Another bump - I would really love to get some possible solutions to try or at least HP confirming that I need to replace something like the printhead?  I love this printer series and don't want to toss it!

[gbuxton5]

Bump again - no one has any suggestions?