6180 DN is about three years old and the black toner cartridge is about a year old. Lately I see black marks at one-inch distance on either side of the paper that run from top to bottom (ten marks on either side) - quater inch from the edge of the paper. Each mark is half-inch wide. This happens with BW or color printing. It looks like holes made for spiral binding except that these are toner marks.
I have cleaned the interior and exterior thoroughly. The toner does not seem to be leaking. Would appreacite trouble shooting tips. Thanks.