Looks like top of cam chain guide broke off, cam chain has worn a gouge out of the side of the casing from the head to the base.I have the sides off the when i took off stator side i found the flywheel was loose... theres evidance of past damage to head, valves and cam seem ok.next problem is the siezed/rounded oil drain bolt.. can i try flush out the bottom end with diesel or something or what checks do i need rather than opening the crank cases?