Fuel Ejecting from carb

[harryjulz]

I have a 1969 40ES Johnson, new to me. It starts and runs but gets covered with fuel. Fuel is squirting out of a hole on the upper right of the carb body next to idle mixture needle knob. This hole is visible in all the repair manuals but they never provide the function it performs. It squirts fuel out when idling down mostly. There is no screen/cover on the carb body and the choke plate is plainly visible. Should this hole have a plug or bolt in it? It looks more like a vent hole. Would a control panel normally cover this opening?

[boats.net]

The carb needs to be removed and cleaned, carb is overfilling with gas.