Shard of metal found in the overdrive

Wonder can anyone help here I removed the farey overdive today and I enclose a picture ( it is dramatically magnified ) of a shard of metal found inside the hole of the overdrive as pictured below its difficult to see inside the hole where the overdrive came out of but can someone tell me how this engages or a diagram of it ? The overdrive itself seems to spin nicely with no crunches etc many thanks Nick

No pic
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