It's been a while now, huh? Wish me (good) luck again... the engine seized today. Actually, it probably was seizing yesterday, but seemed OK today when when we went to use it again; seized after about an hour and it got good-and-hot. We need to use the machine tomorrow, but I have found that air-cooled engines can have "benign" seizure and still live. It think the cause of heating/seizing is because the machine design direct the exhaust so it is a primary source for engine intake and cooling. I'll fix that tomorrow with a die-grinder, make a real exhaust port!