Good afternoon members

I picked up a few machines which have been inactive for a while, one of which is a Stihl 010 av saw. It fired with a bit of fuel in the plug hole, so took the carby cover off to see if there was anything obvious. I noticed there looks be a small brass grub screw visible in the top fuel line. Before I start pulling things apart, does anybody know where such a thing may have come loose from and somehow became lodged in the fuel line ?

Cheers
wce