Thank you for using the Support Forum. Please take a look at the bottom portion of the Paper Specs article from the online support for your machine for information about printing on glossy heavyweight stock. If making further adjustments does not help, then it could be the transfer roller and you would need to have service take a look at that for you. Please consider contacting your support centre for further assistance.
I purchases a Phaser 6510 about a year ago, and have had issues blotchy prints since day one. It seems to be getting worse. Here is an example. That is supposed to be a solid black background, but this issue happens on all colors. The strange part is that the issues are way worse in the center section, and pretty much perfect on the edges (this photo was a piece cut out of the center)
I am using a film free transfer paper. I do not know the specifics of the weights, but the manufacturer said that it is equilvelent to a heavy weight glossy card stock. I changed the settings on the printer for HW Gloss for both the fuser temp and voltage offset. I took them both up to max with very little change. My research took me further to the 2nd bias transfer roller. I removed mine and noticed it is full of toner. I'm not sure if this is normal, or if this level of saturation could be causing my issues.
If this is not an issue, I am open to other options.