RE: servo
If you have never built a gasoline powered heli before, it is critical that you insure the clutch and fan assembly run true (withing 2/1000) using a dial indicator to align them properly. Equally important is to insure the clutch is centered in the clutch bell and that it is aligned horizontally and vertically to the bell, when you install the engine/clutch/fan assembly into the mainframe. If these are not done properly you will have a lot of high frequency vibrations that can cause power system component failures and reek havoc with gyro settings.