I searched our Support page and found this article for white streaks through magenta that may help resolve your issue.
Have a bit of strange problem that we can't fix. We have a light stripe/patch running along the back edge of the machine but it seems to only affect the Magenta toner.
We have gone through multiple toners so that isn't the issue. We have also tried two new Drum Cartirdges along with using the little cleaning stick. No luck at all.