Well, That is a bad break.. but, as my earlier posting advised.. not such a good idea using parts with that kind of miles on them, even ones considered 'Bullit Proof"

No parts are bullit proof.. they ALL wear out

...a chain pushing 200K has wear, I don't care what motor it came out of.
..and for $50 ?? ...and you had it torn down that far anyway ??

Sorry , but not surprised.