Sounds like you have tried everything already, so it would be a hardware escalation: 1-800-835-6100.
Our WorkCentre 7120 has made over 260,000 impressions and is still running faithfully. I just changed the Magenta drum, magenta toner and the R6 Belt Assembly (while wearing gloves and avoided touching any part of the belt). Everything is between 95-100% except for the Black drum which is 45%. I have cleaned the machine using the brush and Xerox instructions and even performed color calibration by following exact Xerox instructions. When printing the color calibration page from the printer screen GUI, everything looks amazing; clear bright colors that I wish came out on everything.
Anything with color when printing or copying (Acrobat, pictures, etc.) all come out faded with what I can only describe as a digital cataract. The colors are all there, but very faded and are not bright.
I even tried copying the calibation page, and it copies faded the same exact way.
Spreadsheets and word documents print fine when it comes to actual black words. If you copy a picture into word and print, it's still faded.
I know the printer is capable because anything printed from the printer screen GUI looks amazing.
I have tried every PCL and PS driver and have tried changing every option I could think of, such as turning up quality, etc. one at a time, to see if it made any difference and that took me hours. Still no solution.
I can't find anywhere inside the printer GUI to turn off "toner saver" if it was turned on. If it's that easy, please direct me as to where I can turn it off. Otherwise, I hope someone can send me in the correct direction because I feel like I'm losing my mind.