What could Fred do from the perspective of the value theory of job satisfaction to better meet his employees’ needs?

Fred, an ambitious entrepreneur, is a long-time admirer of Amazon.com, and particularly of the company’s consistent efficiency. A couple of years ago he took advantage of some strong financial backing to buy a pharmaceutical compounding company. Fred plans to make his company the most efficient compounder in the market, but he also wants to treat his employees well and develop a highly motivated workforce. To accomplish this, he created a nice work facility, pays at the top of the range for comparable firms, and provides clear policies and generous vacation time.
After two years, Fred decided to survey his employees. The results were disappointing. His employees rank their benefits highly, but the other survey responses indicate that they are not very motivated in their jobs.
Fred needs to do something if he is going to meet his goal of best-in-class efficiency.