Exact Same Issue, Xerox Colour 550...like you, still have yet to find a solution
the model was a bit old though
had something like this before. tried cleaning it manually.
I am trying to print Black text on tabs with mylar and the type is fuzzy and there is toner smearing above the text. I have tried lowering the weight by one range, image enhancement, changing the media settings from uncoated to coated - to no avail.
Running a 700 Digital press