I'm getting dark (but not completely black) streaks close to the right edge and along the whole length of each paper. There is a streak of toner at the corresponding part of the drum, but cleaning the latter doesn't help, for the streaks reappear on the drum. I've also tried unlocking, re-seating, and locking again each toner cartridge in turn, as advised by someone in response to another post. However, nothing seems to help so far. There is also toner powder scattered around near the roller that I've attempted clean out as best I could. There seems to be some toner (not sure which colors) leaking out onto the drum and causing the streak, but I've not been able to pinpoint the source.
Any advice would be greatly appreciated, as it's no longer possible to use this 3000cn for any professional jobs and replacing drum cartridge is probably not going to help.
Thanks in advance.
I just replaced the drum cartridge of my 3000cn printer, and the streaking immediately disappeared.
Lesson: try replacing the drum (especially when the printer has been asking you to do so as part of regular maintenance), before attempting to 'repair' anything.
I was able to remove the dark black/grey streak down the right side of the paper by opening the top drum cover, and pulled the drum container up and out and flipped it over. Next, on the blue drum, I noted the accumulation of black toner on the right side of the drum. I rotated the drum manually with my fingers which rotated the blue drum. As I rotated the drum, I wiped with a dry clean cloth across the length of the blue drum. Careful you don't do this on your lap or a clean counter because toner will spill out the bottom as you do this. A little isopropel alcohol will help I think but I didn't use it because was afraid it would melt the blue drum coating. So I wiped away a massive amount of toner, and then there is a rubber paper roller on the top/opposite side of the cartridge and wiped that clean too. I replaced the whole magazine back into the top of the printer, test printed and the streak was gone!