I hear you on the diets! So many people feeding all different diets... from animal protein (eggs, meat, cheese) which is nothing but a slow poison to them, to free-feeding pellets, seeds or nuts. The truth of the matter is that the pet food industry is unregulated so they can claim that something is nutritionally complete while the food is bad for them without having any kind of legal exposure. The other sad truth is that nobody really knows what the exact nutritional needs of each species of parrot are. We do know that amazons are mostly canopy feeders (fruits, buds, leaves) and, much less, ground foragers (grass seeds). We also have one single study done on their wild diet and it was determined that, during breeding season, when the parents are raising young, the parents ate a maximum of 17% protein. We also know that their diet is very high in fiber (all plant material is) and also very high in moisture (plant material being 85 to 95% water) and low in fat (because the seeds they eat are green ones -not dried like the ones we give them). Needless to say, a pellet that has a minimum protein of 17% (higher than what the wild ones eat during breeding season) and a maximum moisture of 10% (HUGE difference!) is not going to be healthy for them in the long run. I've been doing research on parrots natural diets since 1994 when my first rescue, a female redlored amazon, was diagnosed with high uric acid and have reached the conclusion a long time ago that pellets are not and never will be the best dietary option for them (many reasons, actually, I can elaborate, if you wish). I've tried different things but have been feeding them gloop for many, many years because, in my personal opinion and experience, it's the best solution. It's wholesome (organic whole grain and frozen veggies which are more nutritious than fresh), high in moisture (very wet), low in protein and high in fiber, very versatile (works for all species), easy to 'doctor' (I add liver and kidney cleansers and tonics to it daily) and, best of all, from the budgies to the cockatoos, they all love it!
There are several recipes for gloop in the diet section but you can make your own because it's basically a dish of whole grains cooked al dente (they like the grains separated and a bit hard so, althugh it's called gloop, the resulting dish is not really 'gloopy' if you know what I mean - it's more like a pilaf or fried rice in terms of texture) mixed with veggies. I use kamut, wheat, oat groats, hulled barley, spelt, red and black rice mixed with corn, peas, carrots, chopped broccoli, sweet potatoes, giant white hominy, butternut squash and artichoke hearts (everything is frozen except the hominy which comes from cans and the sweet potatoes that I either bake or nuke). I also used to use lentils and small white beans in it but have started recently eliminating them. I was never really happy with feeding parrots beans because it's such a very unnatural food for them and they are a bit high in oxalic acid so I stopped (my gloop recipe has always being and always will be a work in progress because as I learn more, I tweak it). To this cooked mixture, I add steel cut oats (because the budgies love them) and flax seeds all the time but, during the breeding season (but I would not do it for your bird this year because he has been eating way to high protein and you need to clean him up first), I also add sesame seeds and alternate teeny tiny sprouts (I sprout a soaking/sprouting seed mix for canaries) with some soaked hemp seeds.
For dinner, my zons eat a heaping tablespoon of a cockatiel mix (ABBA 1600 C) with nuts (right now, they are getting one pistachio, one quarter of a walnut and half a smallish pecan - but I change the nuts whenever I buy a new supply so they also get almonds, cashews, brazil nuts, filberts, pine nuts -(not often because they are soooo expensive!), etc.
You should also try to make birdy bread - a fabulous way of getting veggies and fruits into them when they don't eat too many of them. I recommend everybody who has a parrot get a bread machine because it's so super easy - the parrots don't care if it comes out too wet or too heavy or too anything! I put all the stuff in it at night before I go to bed, and, in the morning, voila! birdy bread ready to serve - and there is not a single parrot that does't like it! Mine got it this morning and they all know the word 'Pan' (bread in Spanish) so when I go: "UUUUUHHHH, look what i have for you: PAN!" They all come flying and push each other out of the way to get a piece before I serve it