Aleksandra:
Again, show them how their work impacts what your customer is trying to do. I believe that workers really want to do a good job, but in their mind doing something just because the boss says so is often not a good enough reason. However, when they see in very real terms that what they do has an effect, for good or ill, on the customer and the final product, the motivation should be there.
Center your training on what each worker does for the customer. Make the customer speak to your workers, through you. After all, serving your customers is how you stay in business, right? Be the customers' messenger!!
Added: As far as technical innovation goes, why not ask the operators if they have any ideas how to improve their process? I bet they do. Also, don't ask just once, but every once in a while, because the fact that you are asking might get them thinking about it more often. Then, be very careful how you handle their suggestions. Give credit to them for their ideas, and don't dismiss any as "dumb". They know their process better than anyone, even the engineer that designed it.
Hope this helps.