Float Bowl Leaking

The screw on the side is your idle speed adjustment.
If your float bowl gasket is leaking you can replace it or seal it with a gasoline compatible sealer such as Seal-All. I suspect that if the bowl is leaking then you have a needle valve issue. Either there is trash in your valve or the float has a crack in it and is not...floating, properly. This will also cause a rich run condition indicated by your spark plug color and loss of power. Remove the float bowl, inspect the float (see if it floats in gasoline) and clean the needle valve that the float actuates. Get back to us with what you find.
Tom

corgi1 said:

gas isn't by chance running down the tube from the tank(leaky fuel valve,in-line filter?)

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Corgi1 makes a good point here that I missed. Make sure the fuel is in fact coming from the bowl and not a leak upstream. Dry everything off, turn the petcock on and start from there down looking for the source of the leak. I recently had a small drip that at first appeared to be coming from the fuel inlet nipple but it was actually a very tiny split in the fuel line just above the nipple. Naturally the split was on the carb side where you couldn't see it. You should still make sure the needle valve is closing off completely when the float bowl is full and the float is not cracked or has fuel in it.
Tom