Install buzzers throughout the plant and invite employees to hit their buzzer when they stopped from working or progressing. If they are out of material, waiting on a forklift, have equipment down and not working, missing tools or some other reason they cannot continue to do their job. It does not have to be for long. You need to find out who is holding up progress. Yes, your buzzers can be loud, medium or a soft less irritating level, but listen for them. When you hear them, your productivity is dropping behind. They give your workers an immediate resolution to the problem that is holding them up. At that point, as a manager, you can determine who is at fault, what process was not thought out completely or who needs training or guidance.