I rebuilt the carb for my Farmall 300 and finally got the float to not leak. The problem I am having now is I have to set the idle screw in all the way. If I get the tractor down to 425 RPM I have to screw the load needle in to get the tractor to quit smoking and to run like a sewing machine. At this setting though, the tractor is too lean for acceleration and idle. For now I am dealing with the smoke at low idle by not idling the tractor that low. The throttle shaft had a few thousandths of play but I would think if there was a vacuum leak from the shaft I would need the idle screw out further to get more fuel in, right? It was cold here (10-15 degrees) when I tried this, could the oil in the oil bath be too thick causing an increased vacuum and pulling more fuel through the jets? I will be getting warmer this week so I will try again.