You most likely have to clean your toner drum, or clean your transfer sheet.if you use a non Samsung cartridge that was "compatible" there is a chance that the cartridge was refurbished, and some refurbished toner cartridges to do leak.your best bet is to clean what ever parts you can get your hands on, the manual should explain where those parts are.http://www.samsung.com/levant/consumer/printers-multifunction/printers/mono-laser/ML-1630/XSG-support