I hope that you can find it- it's so frustrating to lose them. It's not in your machine is it?
I had just gotten my machine back from it's yearly checkup, was sewing and broke the needle. The ends were still tangled in the thread but the middle was in 2 pieces. Found one and knew i was still missing a piece. Never found it. I was so afraid that it was in my machine ready to do serious damage if i used it. This was at our vacation home so the dealer was 165 miles away. I even dropped the other piece on the floor to see which way it would go.( don't laugh, that little trick has worked for me before) lost that one too, but I knew it wasn't in the machine. I shook it gently- no rattle; took off the covers tec. I finally just sewed on it and there have been no problems. There is berber carpet in there and apparently it eats things like that. Found several buried in it from the previous owners.