Now in this set of pictures I have the dowel loops as pictured in post 12. The first picture shows the plane balanced wing tip to wing tip. You can see that the dowel is significantly out of alignment. I attribute this to how the loops are wrapped on the dowel. The second picture shows the plane balanced but the dowel is still way out of alignment. Worse than in previous post. The third picture shows the dowel loops are as pictured in post 12. Not a balanced setup. The fourth picture shows how the plane hanging in the aircraft loops affects the dowel alignment. The plane is not balanced wing tip to wing tip but the dowel is aligned with the spar.

With your GSS hanging in the loops, move a line just a bit to reposition the plane a little and watch how the dowel rotates. This is why I favor the plumb bob in the center of the rig.

Anyway hope all this helps. You just have to use rig and you learn by using it. It is a handy simple device. I have compared results with my PVC balancer and both are right on. I find the rig easier to use.