DESIGNJET 500 DOES NOT PRINT BLACK

[Winston9]

Help!  My Designjet500 will not print black ink....it did a few months ago.  Black does not show now on the diagnostic print and when I try to print using 'best quality' the lines are blue.  I put in a new black cartridge.    I replaced the black ink cartridge which was very old and the new one  didn't work.  My other three colors print fine.  I have not used this printer much lately - but ran a diagnostic a few months ago - and changed two colored printheads - all the colored print-heads work fine. I am concerned that maybe the inkline has clogged but wonder that the others seems to work.  

I suspect a clogged black ink line - or the black print head.  I am 2 hours south of St. Paul and don't seem to see any HP service shops in this area.  Anyone else have a problem with the black print head?  thanks for reading

[Valsimot]

Replace the black printhead, that will probably solve your print quality problems. You don't need to worry about clogging or air unless you haven't been using a printer for several years.

[Winston9]

Thank you Valsimot for your input.  I did order one last night after watching a video on cleaning the printhead which I tried.  (soaking it on a wettened paper towel - It did  print out some very black work for a short bit but when I put it through the diagnostic print - it did not print a true black again and the message in the display panel instructed for a new print head.  Also I tried the "cleaning printhead" command and that did not help that I could see.  I'm hoping a new printhead will do the trick and seems like ink is coming through the tubes so I am encouraged that way. Thanks again - have a good day.