I just looked at the manual online and the correct CG is 4.25" from the leading edge, not 1.25". Make sure you are using the correct CG measurement. If it does end up needing tail weight, consider putting your receiver battery back further in the fuselage. Remove the covering from a large lightening hole and make something to attach the battery too then just use an extension to connect it. Another tip I recently got is to attach the battery to a dowel then srick the dowl down the fuselage. Adjust it until the plane balances the permanently attach the dowel to the plane.