sounds like you guys are having trouble with your saito 100's. I had to send mine in too. bearings went bad after just a gallon of fuel. Horizon covered it under warrenty. i was just curious as to what the problem was and are the replacement ones better? (i've only run the engine on a test stand because i was using a different engine that belonged to another guy and the plane crashed. oh well, Mojo 60 HERE I COME!!!!!