HP Z3100
Q6659A

Issues with print output
Seeking advice & recommendations

I bought this unit soon after it was released and took delivery in May of 2007.
I've been very happy with the quality and cost.

As a independent freelance commercial photographer I use this to make prints for myself and my clients. I generally don't produce or sell large numbers of prints and as such this printer sees fairly light use.

In approx. 4.5 years I estimate that I've only used about 3600 sq.ft. of paper and under 4000ml of ink (roughly 30-40 130ml cartridges). The most popular size I make is a 30x40 which I can print on 36", 42" or 44" wide rolls of paper. Until recently I was still using the original set of print heads.

Over the years I've learned to calibrate this unit to maintain consistent output. Consistent enough that I generally only need to make a single print rather than 2-3 and dialing in to a target like I had to on my previous printers. 

Here's the problem; a persistent pattern of head tracks on and off the image on the outer sides of the print area;



Previously when I found marks like this I applied 2 levels of fix;
First I would activate a print head cleaning through the menus on the printer and then if that didn't work (perhaps in combination with reoriented the printout incase the content was contributing or exasperating the issue)

 I would then setup for a printhead replacement, but just remove each printhead and clean it thoroughly. 90% of the time this would work and has been enough for over 6 months. But now the problem has returned and I cannot figure out how to fix it.

pattern appears on calibration outputs

same pattern - it appears to possibly related to the carriage changing directions? I did re-oil the rod it travels on.

no change in outputs. At least I can kill the job before it wastes too much paper and ink. The marks make this pattern on the left side of the image area, but also make marks on the right most edge, but more randomly and without a distinct pattern like this. Previously I would just get an occasional small blob somewhere in the image area that would spoil a printout, not such a pattern.

printheads removed, prior to cleaning


carriage that holds printheads (pens). I use a forcep with a half Q-tip that I've dipped in denatured alcohol to remove any ink around the base where the heads seat and find most ink at the ends.

ink collects at the front of the head as well as in the "bend" at the back 

same head (magenta/yellow) before and after cleaning

I also cleaned the reservoirs (spittoons) and all exposed surfaces at each end as best I could.

Drop detector shown with bar code. I cleaned that as well as the flat surface hidden in the photo below the printheads in the "home" position.
My goal was to remove any collected puddles of ink that might be sticking to the carriage or printheads and being carried over the print.