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Maybe the shoe broke off of the tensioner somehow, and got broken into three pieces flying around in the primary - perhaps by getting caught between the gear and the chain? Just a thought...
If you look at the adjuster shoe, it has two bolts that go through it and hold it in the adjuster. In order for it to come off the front and rear had to break off at the bolt holes downward and out. then the middle piece could be pulled out by the chain. Luckily the pieces were forced down by the chain and did not get up over the chain and get between the chain and sprockets.