Hi
Welcome to the HP Support Forums. I understand that you have a re-occurring paper jam issue. I would like to help.
It sounds like you have ran the whole nine yards with trouble shooting the issue. You can check this document for any steps that you may have missed. A 'Paper Jam' Error Displays on the HP Photosmart 5510 e-All-in-One Printer Series.
I have also sent you a private message with something to try. If you are unfamiliar with how the Forum's private message capability works, this post has instructions.
If you have any questions, or this does not resolve the issue, let me know.
If this resolves your issue, please click Accepted Solution. This will allow other people with the same issue to find the solution easily. If you wish to say thanks, feel free to click Kudos.