I am overhauling my XR because it burns oil. I noticed before I removed the cam chain that with the flywheel on the "t" mark ,The marks on the cam pulley do not line up. They are out by about half a tooth. There is no slack in the chain and it doesn't matter which direction I come up on the marks from. Does this mean the chain is worn out ? Can I replace the chain without removing the sidecover ?