BLACK NOT PRINTING

[HVJS]

Printer working perfect well before I went away for 3 weeks.  On return black does not print.  The cartridge is still full, I even tried a different (full) cartridge. and printer ink levels show black as full.  Cleaned printhead and realligned.  Printed diagnostic sheet which had only blue and red - no black.  Tried to scan sheet and printer reported that it had not been recognised.  The cartridges are all OEM but have working perfectly well until now.  I've tried printing a document, copying and scanning - still no black.  Help appreciated.

[8lives · Accepted solution]

Check the printer warranty status: http://h20564.www2.hp.com/hpsc/wc/public/home 

If the warranty is finished try the following. (use rubber gloves)
Remove power to the printer before attempting the following.
Make sure that the contacts on the cartridge are clean. 
Can ink be drawn from the bottom of the cartridge. (touch the outlet with a paper towel)
There is a little mesh filter below the cartridge. (visible when you take the cartridge out).
If the ink dries in that mesh, then no ink will flow.
Dab it gently with a Q-tip moistened in hot water.
It may take a few tries to get the mesh filter unplugged. 
Do a 'clean' operation in between attempts. 

[HVJS]

Unfortunately out of warranty.  Already did paper towel test and ink flowing freely from cartridge.  However, tried several more cleans and wham black is now printing.  Thank you.