Well you get one Kudo for your patience and sticking with this. You get a second Kudo for digging into the manual uninstall/reinstall process, after the uninstall HP app didn't work. Very clear, very thorough. Thanks.
But alas - the third and key Kudo awaits; the original problem remains unresolved: every half inch or so, the leading edges of the lines become indented about an eight of an inch. Then, as the printing proceeds down the page, after another half inch, the lines go back to starting where they should. That behavior continues all the way down the page.
So.... again I did an Alignment. Ana again its print-out looks just fine.
Then again I did a Copy. I put two bank checks on the platen. Again, the image double-printed - ALL of it- the second impression on top of the first, offset about an eight of an inch to the right. This double printing does not occur when I print a file from my computer, which instead prefers the line staggering problem.
But then I thought - hey! I have an older computer, a still-functioning (kinda) Power Book G-4 with OSX10.5.8. I dug it out, ran a print test. Same staggering edges problem! So it's clear - the problem is in the printer, not the software.
Just before the problem started, I installed a fresh HP driver (from HP, not, alas, from Apple) to solve a minor problem, and right away had a paper jam. After clearing it, got an error message: the ink cartidges were stuck. I looked intp the printer, couldn't see the cartridges (they were way off at the left), I so I reached in and pulled on a belt, trying to get the cartridges to move and show themselves. Evidently I threw something out of whack.
So now - do you have a procedure you can give me for restoring the MECHANICAL alignment of the printer mechanism?