On my Tug 1963 621 I had a friend rebuild the carb, the main jet is or was missing the Venturi was in upside down and the main needle I'd bent. After messing around with it for a few hours we took it apart and found what was wrong with it. Another friend took and made a new main jet that seems to work. Originally there was a low twntion spring under the float, my friend took that out. Does that need to stay in to support the float? Now if we ran it out of gas and the floats go into a rest position then add gas to it it pours out the carb air intake. But if you run it and shut the motor off its fine. Any ideas?