You guys with your 59Ms did inspire me to get my Mighty Mac running better. The 5 horse B&S only ran just above idle when I brought it home. I purged the old fuel, flushed the tank, fished out the part from an old gas cap vent, and it ran much better. So much better that the hammer mill stopped turning. This thing is rusty, so I suspect bearings or centrifugal clutch overheating, and not behaving nicely.