Yellow and Magenta drum problem

Good day I have an OKI C6100n printer and find it prints Very good, but my problem for the third time in a year the yellow and magenta drums is not allowing me to finish the toner after the use of about 60%
I am having some big streaks, upon viewing the drums the ink is not spreading smoothly over the roller of the drum.
NB there are no streaks in the drum. My name is Doreen and some one in new york does my ordering for me. Thanks as I await your replycribe your c6100 okidata drum problem Proble