The main problem in my mind is that the puzzle offers no feedback to the user that they are on the right track. For that matter it offers no feedback that they

The main problem in my mind is that the puzzle offers no feedback to the user that they are on the right track. For that matter it offers no feedback that they are on any track, right or wrong. It's just random motions with no particular motivation. Some kind of light, or bell, or even a plexiglass version so you could see the balls moving about inside would be better.