Why do my copies have stripes on them? Why do my copies have stripes on them?My Canon 6016 copier

Question

Why do my copies have stripes on them?My Canon 6016 copier prints fine when cold but after about 10 copies dark streaks the direction of the paper feed begin to appear. At first they are light and they darken each sheet. They were only on one side, now they are in several places across the page. I have cleaned the mirrors. What else can I try? Scott