Expansion plugs such as the one you might find on the choke housing will sometimes come loose, fall out, or perhaps you just needed to get inside for a good cleaning. The process explained here is for those types of passage ways that have no fuel such as the choke housing clean out plug.
Remove dirt or burrs from the seat in the casting. Install the expansion plug with the dome side outward.
Keep in mind that this type of plug is for those passage ways that do not have fuel flowing through it.
You can find clean out plug kits on Mike’s Carburetor Parts web site.