Apple HP DeskJet 840c InkJet Printer "new colours faint" Questions

Colours print ok, black is printing faintly in with white lines through it, have tried new black cartridge to no avail. Please can you tell me what the problem is THERE MAY BE MINUTE PARTICLES OF DUST

...colours on a Konica Bizhub C253 are faint on a Mac. When we print to our new (plastic wrap just came off) C253 from anything other that Adobe software on Mac OSX10.5.x the colour is at about half ...

DELL 5110CN PRINTS PRINTS LIGHT GRAY NOT BLACK! RAN LOW IN TONER AND PUT NEW ONE IN AND NOW AFTER 100 PAGES PRINTING LIGHTER AND ALMOST CAN NOT SEE. CHECKED CARTRIDGE AND IS FULL OF TONER. ANY IDEA???

...new) and when the printer prints, it ignores the colour except for a faint green and yellow tinge. Also, everything printed has white lines through it. When I used the Nozzle Check function, it ...

...faint line cracks/creases on green flexible drum sheet. Any possibility of repair/polish/coat with something? I'm in South Africa, Drum costs twice the price of new unit. Will never ever buy a new ...

...years old....but this is a relatively new problem I have instructions on how to clean the developer blades. It should fix the faint printing that you are experiencing. It is posted in my Tips

...new cartridge but the pages are still faint and half way down the text is still faint. Any ideas? yes you will need the black to print in full then make a cleaning and then a test page then it should ...

...faint, looking like 50% of the true colour. Both ink cartridges were brand new. Checked out the manual, done all i can on the trouble shooting, re-loaded the cartridges, done the head clean, changed ...

...colours are much improved then the printer requires a new Transfer roller. 1. Open the Right Door. 2. Remove the Transfer Roller while opening the shaft holder (white color) levers found at the left ...

...new cartridges and it still wont print...its print a really faint yellow you can hardly see and when i test print only the colour prints. but if i print colour nothing shows up Sounds unlikely but ...