I would like to start by thank everyone for sharing informations about EPSON print head problems.
Here is the problem I faced yesterday. My 9900 has been turned off for 1 month. The last time I printed, everything was fine.
Yesterday I turned it on and let it make its self cleaning. I made a nozzle check just after.
My LLK was partially printed...
After few cleanings, I decided to dismount the print head to manually clean it with warm distilled water.
I started to dive the print head in 1cm of distilled water, and gently shaked it. I changed the dirty water twice.
When the water was no more dirty, I took a syringe and really gently aspired from the LLK whole behind the print head, until the liquid was pretty clean.
I thought it was not too much to do that with all colors, so I aspired from all color wholes.
Finally, I put the print head on a paper towels and I really gently push some air with the syringe in each color whole to help drying it.
Then I put it back in my 9900.
I turned on my 9900 in Maintenance mode (left+down+right). When it was in "ready" state, I wanted to print a test image and I realized that "Matte black" was selected while it was PHoto black before... So I switched to Photo black and it started by a self cleaning...
The self cleaning took a very unusual long time and ended with an error message saying it was not able to.... end the cleaning.
the 9900 asked for retry or continue. I pushed "continue" then it started to switch to Photo black.
After switching finished, I checked my waste ink tank... It was totally empty !! No ink went through the print head nor during the switch neither during the self cleaning.
I tried to print a pic, and the printer left me a beautiful white paper !!
I disassembled a second time to check electrical connections. Everything was well connected, with no inversion...
Then I tried to send the print head serial number through servprog, which has been well sent, but nothing changed. Still white paper when printing.
My print head had been replace last year... But I admit I don't print everyday... It happens that the plotter stays switched off for 2 or 3 weeks.
Did I forget a step ? Do I do something I shouldn't have done ?
Thanks in advance for your help, and I hope I didn't kill my print head !