Purchased my '08 Burgman 400 used this spring and brought it into the local dealer for its 14,500 maintenance (wish I had the time, patience, and tools to do the work myself $605 later). On my receipt under the recommendations it said "drive shieves grooved from consistant rpm opertion." First, I don't know what drive shieves are or what their purpose are (as you can tell I am not a mechanical person), and second, is this something that can wait or should I have it done with my next maintenance work? Also, I do not have an owners manual, is the next service at 18,000 miles? Thanks....