Officejet Pro L7780 Printhead Problem

[Raymessier]

I have been using HP printer officeJet Pro L7780 I have 4 of them, so to save on printheads I bough used printheads to see

what I can do. First i dismantle or strip the printhead completely.

I found stagnant black under the screen filter for all color yhe black ink was the only one.To clean the printhead it is a messy job you have to be carrefull. to removed the fillter you have to make a special tool, a long needle that you bend the pointed end one sixteen of an inch that you insert in the slot at one end  turn the needle an pull it is stif.

to clean it is a pretty long process.you use only warm water hot water may damage the head, now in a tub ho I forgot to mention to removed the top be carefull first remove the ink dupply 

[dukenukem]

In response to "billmill"'s post on 7/10/2012):

This is exactly my trouble.   I bought the genuine HP new replacement last week and it ran OK for an initial test page, then after the next restart it started displaying "(Printhead(s) Problem" and "The following printhead(s) has a problem: magenta/cyan(M/C)."

Was this ever resolved?