That sounds like some good advice, dtg. I would like to add a few suggestions of my own. The age/mileage of the engine in question might be something to consider. I had the same problem with my first engine, and it turned out that the piston rings and crank bearings were shot. The engine was a year old, had very heavy mileage, and it also turned out I was using marine oil, which is very bad for air cooled engines. Hopefully its not a mechanical failure, but might not hurt to check it out. Also, perhaps the clutch pads are completely worn out. A new set only costs about $15, just make sure you get the right shape (round or square).