I recently started getting a cyan haze all over my color printouts, and image ghosts going up my page. Sometimes the problem will happen with other colors too, but more with cyan. Initially, I was able to get rid of the problem temporarily by doing a developer cleaning, but now even that has stopped working, as the roller on my imaging drum never gets cleaned. I've tried changing the imaging drum, transfer roller, fuser, developers, and HVPS, but none of these changes have fixed the problem. The printer has had a relatively quiet life (15,000 sheets). I have plenty of spare parts from retired printers to swap. All I'm lacking is a clue :).
Our 5100cn printer has the same problem. Have recently changed the drum and transfer roller, BUT started using non-Dell ink. (Could this be the case with you too??) Someone recommended changing the fuser, but I can not find it on the web site. Also, the drum set listed for order on the website is the wrong part, and because I called I was alble to get the correct one. Today, I just don't have all day to talk to Dell customer or technical service -- it can take up to 4 hours and still I walk away with no answers - not worth the frustration.
The company that makes these printers for Dell has a trade secret on the toner formulation. Compared with 3rd party toners, it is not the same and the "other stuff" will eventually ruin the inner workings of the printer. (Fuser won't fix this)