Fixing a Stuck Spoke Wheel Truss Rod

This neck on this Sqoe SBMS500 Five-String Bass is back-bowed, leading to string buzz in the lower frets and high action at the other end. The truss rod should be loosened to induce some relief, but it's stuck and cannot be adjusted. Applying downward pressure to the ends of the neck, the center of the neck, and the ends of the neck once again seems to have worked. The truss rod is no longer stuck, and can now be adjusted.