Key 2 – Hint 6

The left and the right wheels can be rotated freely when the middle wheel is looking towards the right or the left wheel correspondingly (see the video)

Rotation of the middle wheel always causes the rotation of both other wheels. For example if you want the middle wheel to come to the position of 4 and its current position is 3 (the difference is equal +1), then set the left wheel on 3 (2+1)