When printing or copying? If printing then likely you have a bad toner cartridge or a bad toner or drum, depending on the device you have. If it is only on copies, is it copies from the document feeder or using the flat glass? Debris on the adf slit glass is the most common issue we find with clients. Lift the ADF lid and clean the glass on the left side of the scanner, usually it is a separate slit of glass about 1/2 in ch wide.
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