First of all, the 7 STEP human verification necessary to post anything is RIDICULOUS. This forum is so wonky, but very informative.
Hi, I manage a print lab, and I've dealt with all kinds of printer and scanner issues over the years, but I've recently been plagued with an epidemic that has me pretty stumped:
We print on all of our printers nearly every day, but over the course of week or so, I've had five printers suddenly exhibit very similar problems. my 11880, 9890, two 4900s and 9800 all started giving me white horizontal banding. Nozzle checks are perfect, ran head alignments (uni and bi consecutively on all) to no avail. I can get it to change, and sometimes get better with paper feed adjustments, but not disappear entirely. the 4900s have thin banding at regular intervals, although today one started out with thicker, dark bands at more irregular intervals, then turned back into thin white regular bands over time. All the printers exhibit it primarily in the shadows. the other 4900 also prints a single vertical dark band on the left side now...
Happens on rolls and sheets, though rolls seem to be worse. Also, the 9890 seems to getting better. However, if you look closely, the dithering pattern seems to be pretty shitty and spotty, often with vertical banding to some degree.
Also, after much fiddling with feed adjustments and alignments, vertical banding became more and more apparent on the 9890 and 11880. Tried different papers, surfaces, etc, all very similar. Look at the banding though, I've never seen it appear in this sort of tapered shape. If you look closely, you can see vertical AND horizontal banding on the 9890/11880.
9800 had the least banding, but still apparent, though it seems to have gone away over the weekend, however when I came back, a huge portion of the MK nozzle check was missing, which never happens (this thing has always been an indelible workhorse). After a few cleanings it was good, and seems to be relatively stable now.
I have reinstalled the drivers, and tried everything I know how to do.
HERE'S MY THEORY... tell me what you think:
We left the lab closed for 4 days over thanksgiving, and the problems started trickling in when we got back, and gradually infected all the printers. Perhaps it got really dry for a few days, and dried out the carriage lubricant on all the printers (except for my 7900, which seems to be alright, but it's also the newest, so perhaps the lubricant is more resilient).