A coil spring will lose free length when it goes away. I would think a torsion bar would also not come back to it's original state. Been awhile since I've fooled with them, don't recall if the hexes are perfectly aligned when new and I don't have any laying around, but I would compare the alignment of the hexes with the alignment of a known good or new bar.

If you keep tightening and it keeps dropping, my guess would be that they are toast.