Like prior posts said, it's built into the transfer unit mounted on the right door (drum access door), again I'd suggest calling in a tech to clean it properly, it requires some disassembly to clean/empty properly.
I had the fuser and all of the rollers replaced a month ago.
I emptied and cleaned the black powder in the unit under the fuser just now. Still says that the Used toner case is full.
Yeah and that unit can be messy to clean, especially without a toner vacuum, not recommended to do without one.. the unit has to be removed and disassembled (a bit) to clean it out (properly).. in my opinion!