I think I know the answer to this question, but I'll ask it anyway. I noticed five broken teeth on my rear sprocket. All fresh breaks that I believe happened yesterday. The sprocket is a SunStar aluminum 51T, which is about two years old. The chain(O-Ring) has plenty of room for adjustment on it still and the counter shaft sprocket looks good. Do I need to replace my chain before I put my new sprocket on ?