I just bought a used 4 star .40 and I'm not sure if it's balanced correctly (no plans). I remember something about it should balance at the main wing spar and it does, more or less. When I flew it, it was nosing up quite a bit and I had to apply a lot of down trim, but it still didn't seem quite right. I later applied about 2 degrees down thrust (washers under rear lug screws) and that helped somewhat but it's still a little squirrely. The airframe seems straight and true. Does anyone know what the C/G ought to be?