OH! Did I mention the exploding L7780 printhead?
A couple months ago, I noticed that every page was coming out of the printer with a giant blue splotch on it.
I tried all the self-tests, alignment, cleaning, and everything else built in to the printer.
Per HP’s instructions, I installed a brand new cyan ink cartridge (the old one was still usable… until I replaced it!)
No difference.
The problem?
The printhead had, basically, exploded.
So, now I have 2 open cyan cartridges… I hope they don’t dry out (I put them in a plastic bag).
In this case, it seems likely that HP knew these things were a problem… because they instantly replaced it without my even asking.