Before you tear your carb apart, just make sure you have fuel getting to the carb first. This series was notorious for debris getting caught in the pickup elbow at the fuel tank, or, if it has a fuel shutoff valve close to the filter, debris can get caught in the valve as well. Pull the fuel line off the carburetor and point it into a container. Crank the engine. If you have good fuel flow, then issue is in the carb. If you have little or no flow, issue is a restriction in the fuel lines or possible bad fuel pump. I had one of these that ran fine for a bit, then acted like it was running out of gas. The problem was a spider body got sucked up the fuel pickup and made it to the shutoff valve. It would float back down the line when the tractor was sitting. Then the tractor would run a few minutes until the spider body made its way to the valve again. Hope this helps!