Note: see HP Photosmart 6510 for the printer specs.
The axis of a gear broke after having put stapled sheets of paper in the printer. It was a 15 mm long plastic rod (diam 1/8“). I made a hole where it broke and then bought a 1 m long replacement plastic rod (no less) with approximately the same diameter. As it was a bit wider (diam 0.4 mm), I had to enlarge the hole in the plastic base and in the gear.
Now, the teardown.
You will need T8, T9 Torx and Philips screwdrivers. Screws are highlighted in yellow in the following pictures.
Remove the cables (screen, speaker) and the rollers cover.
Remove the rollers.
Note: I forgot two screws in the process, I can't find where they come from…