Printer exercising the mechanism before every job

[tympan]

My HP 7720 is working fine EXCEPT a few weeks ago it suddenly started moving the printhead back and forth repeatedly before every print job. The EWS says it's using update ELLISXLP1N003.2042A.00 from 2020-10-12, which matches the timescale.

When it finally decides to print, it prints normally, but it performs this long, complex alignment-type movement of the printhead every time I send a job to print. This takes about 1 minute, and then the job prints correctly.

This happens no matter what host I print from (I have tested it from my desktop, laptop, iPad, Android, iPhone, Windows, Mac, Linux devices and it's always the same) so it's NOT a driver problem — it's something internal to the printer. 

1. Has anyone come across this behaviour before?

2. How can it be turned off? 

3. Is it a bug in the update? It started at that time.

[Valsimot]

Does it act the same when you copy a document from glass?

[tympan]

Interesting question so I just tried it.

Yes it does. Press Scan and the printer mechanism cranks away backwards forwards side to side buzz click for about a minute, excatly like when you have put in a new cartridge. Then it starts to load a sheet of paper, realises that it's supposed to be scanning, goes off and scans the page and then prints it just fine. 

[Valsimot]

That confirms that this new "act" is in the device, nothing computer-related. There is nothing much you can do, try a factory reset.

[tympan]

OK, thanks very much, I'll give it a try. 

Still a bug that needs fixing, though, given that it was introduced in the last update. Is there somewhere formal it can be reported.

[tympan]

I did a factory reset and it had no effect. 

My guess is someone inadvertently added this bug to the latest firmware update. Domestic and office printers do not need to recalibrate the printhead mechanism at the start of every job and in between every page.

Is there a way to revert the printer to the previous update?

Or to log this as a bug with HP?