Before you remove the weight, try this.

On a nice calm night, fly straight and level and make sure the ailerons are trimmed so it flies "Hands off"

Now roll to inverted and see if it still flies "hands off"

If one wing is heavy, it will need to have that aileron lowered to make it fly "Hands off" But when you fly inverted, that aileron is now "Up" which is pushing the heavy wing down - so it will want to roll out of the inverted position.

But if the plane is laterally balanced, even if the ailerons don't seem to be even, it should still fly correctly whether right-side-up or inverted.