Aficio MP 2000 Black Stripes after changing developer

[kopiary]

Hi Everyone.
I have a big problem. After changing developer, drum and cleaning blade machine make 6k copies, and then black stripes on the back of paper starts to appear.
Magnetic roller cleaned and charging roller was changed to new one. TD sensor i also cleaned. And nothing changed Toner = Katun.
Someone have this same problem and find a solution?
Thanks for any help and sorry for my english

[Zeldaman]

[barratec]

Re: Aficio MP 2000 Black Stripes after changing developer

Zeldaman is right, change transfer roller!