Hello again, I was hoping someone could point me in the correct direction here.
My Phaser 7750dn, has had a lot of work lately,
Refurbished image and process controller boards
New frame with the controller board
New Developer for the yellow.
new imaging units on Yellow and Magenta.
New toner cartridges on all.
I'm out of ideas, I have no repeating defects, smears or lines, the printer always prints fine from any PC, but when my atr dept uses their Mac with 10.8.5 OS and latest Xerox Driver for Mac 2.0.14 it is a hit or miss as to whether or not it will give a clean print, they either start to print clean and normal then it fades away on the next image, sometimes it fades on a omage after it started ok, other times it just prints faded images. I'll try to attach an image of about 4 differect prints maybe someone will have an answer for me. Thank you.
Since PC works and Mac doesn't, you are only troubleshooting the driver or the port.
Uninstall the printer and install it again, but do so manually using an HP Jet Direct port (This is the same as a Windows RAW port)
If that fails you would need to install either a newer or older driver, though I am not sure where to obtain either since it is no longer developed for and Apple doesn't distribute for it anymore either.