1. There is an ice wall on the left side of where the gear is turning. Take the ball first to melt the ice wall on the left and put the ball on the device on the left.
2. After completing the puzzle, go to the far left, use the yellow ball to melt the ice wall and put it into the laser device.
3. The laser will pass through the two gears and hit the mirror. There will be balls in the houses on both sides of the central channel.
4. You don’t need to take the yellow ball out. You can put it directly into the device and enter the plot. The light will shoot out and melt by itself.