Unless the toner wipes off (smudges) or flakes off, it won't be the fuser.
It appears more like there has been a toner spill internally.
The Phaser 7400 requested a change of cyan, yellow and magenta imaging units which we did. Then it started to print like this. We've also changed the transfer unit as there was excessive amounts of toner on this. After installing it, we tried to print and got same result. On checking the new transfer unit, it was covered in toner.
We don't have another fuser to try and replace – is this the problem.?