I just removed my primary to send to james and noticed there was a lot of black fine dust in there. Inside the cover was clean. I only have maybe 200 miles tops on these and it was spotless when I put them in there. They now are starting to get a flat spot on them. I had them in my King Quad too and th esame thing happened, so bad that the covered wore to where they were shot. What causes this? Seems like the round covers are better for wear.