Dark colors not adhering to page

We have a Xerox Phaser 7800 and there is an issue with the toner not adhering to the edges of the page specifically the 12x18. Seems to be along the edges more and with darker colors . We have tried changing to Xerox brand paper and changing all the settings. What could we be overlooking?

 

I used to have a C60 that used to do that on heavy media.
Check the edges of your fuser roller for build up. When the lamp in the roller starts to go bad, toner will fail to adhere along the sheets edge.
Ultimately the roller will begin to collect toner, causing the issue to increasingly worse..

 

I thought you were leaking yellow developer too - but then realized those were little flowers

 

Hi
Your problem is one of several possible things. 1 the CMYK break down of this affected area is above the recommended figure of 240 (add up the 4 colors it should be less then 240). Secondly could be fuser related but i doubt it or it is a stock setting issue ie not the correct weight set. But i would almost guarantee its the first suggestion.