LOL
I found this to be pretty easy.
Solution to 23 is to put the screw underneath the ball with the rotating board, make it so it angles the ball and rolls off and onto the cog and into the other ball.
You don't even need to use the other rotating board!
I could seriously cut out 2-3 pieces on 60% of the levels and still make it work.
Good game! I only used the "see solution" 3 times. Not bad!