The life a starter is not counted in miles but starts.The starter is the original one and was wore out it had over250,000 miles on it.
The starter is splined to the drive gear in the engine. It's connected to the driven gear by a chain. The starter does not contact the starter clutch assy.The only thing that starter touches is the starter clutch.
With the amount of miles on the bike, I would be willing to say the chain the starter turns to start the motor,has alot of slack in it and is hitting the sides of the case. If the original gear was used, it might have worn down to the point its allowing more slack in the chain. Chains stretch, but when the motor speeds up, the chain tightens so its not noticeable.,,