Well firstly, I believe he's a mealy amazon. They are known for having a rolled in meal "flour" look to them. Some orange wings also have that look. So, that slightly dusty look on his back and wings might just be normal for him. I kind of like that look myself. That said, amazons are notorious for having vitamin A deficiencies. I'd get him going on some pellets as a main diet with seed as a minor supplement. Alternately, you can do a sprouted seed based diet, but you'll have to do some research before you can do that safely. My first amazon had a Vit. A deficiency when I got her. I started out introducing pellets and cooked sweet potato. Over the course of 2 weeks, I drastically reduced the amount of seed in her diet and increased the sprouts, pellets and orange and green veggies. It was a night and day difference in the bird. Diet made a bigger difference in feather quality and color than multiple baths did. Amazons simply need vegetables and fresh food to be a significant portion of their diet. Pellets are better than seed, but nothing replaces fresh food. I'd shoot for fresh being at least 25% of the diet if not more. Mine get about 50% pellets and the remainder in about equal parts sprouted seeds and fresh or cooked veggies. At the moment, they are getting hardly any dry seed.
