Where does this piece go in a Piaggio Nrg 50 carburetor?

I got a 2002 Piaggio Nrg 50 scooter that does not want to start. I removed the carburetor to clean it but ended up with one extra piece I cannot remember where it came from.

I believe it was located in the reservoir (11) but I cannot seem to find where it is suppose to go. I also cannot seem to find this piece in the diagram below. Super thankful if there is anyone who can guide me in the right direction.




https://partsrepublik.com/en/moto/piaggio/nrg-mc3-2002/carburettor-2-