Hello pricklycactus,
I searched our online knowledgebase and found this article that may help you. If this doesn't help you may need to schedule another onsite visit from a technician.
I have a new Phaser 6510 which i use on Windows 10 and mostly Adobe illustrator
I have just had the transfer roller unit replaced as i was getting big black lines down the side - the engineer said replacimg this unit (on a new machine!) should also help with the blotchy printing. It hasn't!
I mostly print text, big bold text, as I sell A4 prints with sayings on them.
Both the black & coloured prints are blotchy and the black is nearly dark grey.
Any ideas on how to fix this?