Missing Carb Screw

[atlhokie]

I have a missing screw on my carb next to what the service/parts diagram shows as the idle needle. I searched the forum and saw someone else posted a similar post a year ago, but had no resolution. Once the boat is running, after a few seconds fuel starts to come out of the hole but I can't find out what the replacement part should be. I posted two photos - any help would be greatly appreciated!

2003 Tracker/Mercury 40hp engine serial #0T729471
Carb serial / model #: 3301-824854-c1

[boats.net]

Looks like that is the vent hole, if gas coming out that hole then float valve is not seating properly. Remove and clean carb.