this motor looks in great condition but won't start after sitting for a while. The carburetor needed to be cleaned and as I was there I replaced the float and needle valve. If I pour a little gas into the carb., it will run until the fuel burns off. I checked the fuel pump and that is working. There is this knob Lean/Rich on the front that has a cable into the carb. Perhaps that is stuck closed in the carb not alllowing gas to flow through? I cannot see how to take that cable apart from the carb to investigate. Any ideas? Thanks