ORIGINAL: LouW
I trust by now you have the cg moved rearward and that has made it better. However remember that an aircraft with a symmetrical airfoil with a zero zero incidence setup will always require up elevator to fly level and down elevator to fly level inverted. Otherwise the wing will have no angle of attack and will develop no lift. The amount of elevator will vary depending on wing loading but will always be necessary.
That just isn't true. Been there, done that - balanced a plane that was in-trim hands-off upright AND inverted. It all depends on the CG location and a stab size that allows a CG location at or behind the AC of the wing. Upright the rearward CG pulls the tail down until the stab reacts and balances the plane at a positive angle of attack. Now, flip the plane over, and the rearward CG pulls the tail down until the stab reacts and balances the plane at a positive angle of attack. See pic: