All colors or just with one of them ?. Print colors separately to see which cartridge is the problem.
Do the following remove the magenta cartridge and grab at both ends of the developer roller, rotate it about two turns and see if the toner is even in all its surroundings (this is to see if the developer roller is working well and finds no imperfections)
you tell me
Surely you have mishandled take out the roller clean it with a clean cloth and moistened with water then pass another cloth of toilet paper giving a drying revealing pad and again arms