I'm doing up another bike that was my sons old VMX that got hardly any use. The front sprocket is original so you can imagine how little use its had. Probably 7 to 10 hours maybe. While I was checking things I came across the usual bent swingarm shaft. This one is only slight but pays to check. I use a cut down drill bit in my Tenshock bike which will never bend. You could also use a cut down pin punch possibly. I thought this vid may help out.