Hi, I'm Robert and I'll be helping you with your printer question.
that is usually a bad drum unit.
the drum unit is what takes the picture of what is to be printed and magnatizes it to hold the toner in the right place so it can be fused onto the paper.
when the drum goes bad it doesnt hold it well enough so you get shadow images where the extra toner that didn't stick gets fused.
on that printer the drum units cost almost 200 bucks per color
If it is more than one color doing it you might have a power supply problem where the drums are ok but they aren't getting enough power to do the job.
so if it is just one color i would say you can just buy the drum and it is user replaceable
If it is all the colors i recommend having somebody local look at it before you spend any money on it.