I have a GP CG machine. The manual says CG should be 4 1/8 inches back from the leading edge of the wing which I have checked with the CG machine and by measuring with a tape measure and marking the wing. The fuse does not allow a lot of mounting options for the battery so the only thing I can think to try is getting a battery that is 4 flat cells instead of 2x2 and placing it behind the servo's.

The only way I can get the plane to balance is to take 18 of the 1/4 oz stick on weights and set them on the horizontal stab.