Shingo told story of a poka-yoke he developed to make sure that the operators avoided the mistake of… 1 answer below »

Shingo told story of a poka-yoke he developed to make sure that the operators avoided the mistake of putting than the required four springs in a push-button device. The existing method involved assemblers taking individual springs from a box containing several hundred, and then placing two of them behind an ON button and two more behind an OFF button. What was the poke-yoke Shingo created?