Hello,
The issue sounds like one of the toner cartridges are leaking or there is loose toner powder in the printer. In this situation, you can try removing all of the toner cartridges and inspect the inside of any for any loose toner powder that can be wiped up with a damp cloth. You can also inspect the toner cartridges to make sure they are not leaking/damaged. Once you reload the toner, you can perform an ITB and fixing unit cleaning using the steps in the link HERE.
