I had not seen the example you showed in the first post... sorry.
I would say ink starvation or air in the printhead. I've had heads with air in them that would print fine and then slowly die out. It looks like banding, but it's more that the nozzels are missing rather than the lines overlapping.
If the ink tubes are primed, I would replace the printheads. Looks like grey.
In fact, grey would make sense because not all prints have that color in them. So it would show up more in some than others.
How do i prime heads? do i still need a priming heads for it? or i can use the working printheads in there?
If you have air bubbles in the ink tubes, you'll probably have to replace them. I don't know if you can prime those with a syringe or you have to buy the set-up heads, but one of those should come with new tubes. Try the rebuilt ones from LPS. But you'll also have to buy a new grey printhead, because as far as I know, there's no way to get air out of the printhead itself.
But before any of that, you'll want to check the stuff Kiran went over.
Actually, looking back at the thread, it was Kiran's first suggestion. There's even a link pointing to the syringe. That's for air in the lines. Get the air out of the lines, and then if it's still happening, replace the heads. This thread is way too long for this problem.
I recommend the syringe method over the setup printhead method. The setup printheads are designed to allow air to escape until the ink reaches it, so if you have air in the middle of the tube but some ink towards the head, that ink will hit the setup printhead and stop it from allowing any more air out. Plus the syringe is reusable over and over.
If you're really desperate, I've seen these things on ebay for 'cleaning' a printhead.. and it should allow someone to prime the actual head.. but I think it would be much easier to simply replace the head.
For HP72 88 940 HP Z2100 Z6100 T610 T1100 Printhead Cleaning Kit Maintenance Kit | eBay
Plus I don't know where you're supposed to get the ink from. Another ink cartridge perhaps that you sucked the ink out of. Sounds like a recipe for a complete mess if you ask me.
PS - Note what the ebay listing mentions: This tool is mainly for the problem of air-entering to the print head 、vertical and horizontal blank stripe printing.
Also, I would like to know (as I've asked twice now) are you using original, genuine HP ink cartridges?? Or are they refills/refillable 3rd party inks?
Last edited by Iowatech; 06-24-2015 at 12:55 AM. Reason: I began by being a jerk about this, but that was wrong. We all miss something from time to time.
Ah, somehow I missed that, sorry!
Did the IDS diagnostics and everything went OK. Those bongo or lifters are properly lifting up and goes back in place. It prompted for a head replacement the other day and users replaced the Gray -PK and MK-Yellow. But when i tried to print an image with a more concentration on gray or light black, the same banding still happens, for any other color it does not. There is no way to visually check the pipes for air bubbles as they are covered.
We are using genuine HP inks, this all comes from our US branch, with all the box intact and sealed.
I dont know what is my next move is, i guess im gonna try that syringe thing. See if there is any progress.