I had similar problems with my O.S LA at first.

Take out the glow plug and open the carb and take off the fuel supply line. Turn the engine over and spin the prop by hand forwards and backwards a number of times.

Set the engine/plane in the sun or at least outside for say an hour and come back and hook up the supply line and put in the glow plug. This time let's all the extra fuel evaporate.

However many times you been turning over to prime cut that in half or not at all if you have an electric starter. Put the ignitor on and start spinning the engine - may take a bit. Once it cranks your set.

After I did that the first time I never had a problem with too much fuel accumulating and causing the lock and the prop to back off.