What is the usual diagnosis or outcome when an HP C6280 AIO won't print a correct Self Test Diagnostic from control panel? It printed it one (won't print another because of multiple errors); was missing ALL data from boxes & sections of 2 pg. report - except color print test boxes (looked fine). Just printed report sections headers & data boxes.

Gone through usual printer reset steps: power reset; clearing hardware error codes via "secret menu," then unplugging & waiting 60 sec.
That clears 1 (or more) errors, but they re-appear. The errors just rotate; clear 1, another pops.

Carriage or paper jam: (neither true); carriage moves easily by hand - isn't "jammed" when reports it.
No paper or bits. Took lid & top cover off. No paper bits that are visible - front, back, inside paper tray area, w/o dismantling entire unit.

Ink system failure: printed perfect text, lines & color boxes on the partial self test, after that error appeared & was cleared - several times;

pump motor stalled.... DON'T think ink motor is stalled or not working. Printed perfect lines, headings & color boxes on the one self test (lacking data). With top cover off, can see all pump gears, belt turning normally in warm up. Pump sounds normal during printer prep.

Paper pick up rollers NOT turning - that's true (except for ONE self test w/o the data). They turn easily by hand; not dirty - just don't engage.

Is it just fried? With so many errors - most seem false AND unable to print accurate self test diagnostic, not sure this is just a "reset" issue.

Had a power outage - but it was on surge protector / UPS w/ voltage control - ALONG w/ modem, router, VOIP ATA, PC, monitor. None were damaged.

Tried plugging printer into wall outlet - no change. DC voltage of printer adapter checks OK w/ meter.

IS it a POSSIBILITY, though AC adapter voltage is OK, it's not delivering correct 1560 mA? Not sure how to check DC mA of AC adapter - any advice there?

It cost $130 after tax - 4 yrs ago (at steep discount). Light use. If it's toast, not sure I'd buy an HP (not just because of this - more for HP's apparent declining? reputation). For avg home use - All In One types, wondering which brand now has best satisfaction, reliability AND least trouble using generic ink? Maybe they're all junk now. As in now, 4 yrs of light use may be avg life?

DON'T want one w/ colors combined in 1 or 2 cartridges.
Thanks.