My husband and I found ourselves in a similar situation after adopting our blue front amazon. From what we understand, he was kept in a tiny dog crate for the first 10 years of his life, with no perch, little human interaction, and most likely poor nutrition/mental stimulation. Boy was he ever the challenge of a lifetime! You must first understand that every parrot is an individual, and some will simply NEVER enjoy being petted. Parrots are highly intelligent, and do deserve respect if they are not the petting type. Affection and interaction with humans and their own can be achieved in other ways (besides stepping up and towel training, these are musts for parrots to learn and tolerate).
Since you have other parrots, you should be familiar with "cues" they give to show interest in something, and use that to your advantage to gain trust. Food is always an excellent trust builder with birds, especially when teaching an mature parrot with trust issues that your not there to hurt him. Small treats of a favorite food can be used to help the bird take the first step onto your hand as well as to desire to, say, sit on your leg or simply not be terrified when you walk by. Also look for other cues your bird is interested in something you have. Our boy took an immediate interest in us brushing our teeth and taking our morning vitamins. We took that as an opportunity to make him feel welcome in our "flock". We cut off the bristle part of an old toothbrush and sterilized it, then gave it to him. You could see much of the fear melt away handing him an old toothbrush handle! He always has one, and their one of his all time favorite toys (no clue why). We also started giving him a pistachio when we were taking our vitamins. Within a few weeks, we had introduced him to the concept of a "routine" and he expects his pistachio every morning. After seeing positive results "including" him in our morning routines, we began bringing him on a t-perch to the table for breakfast and dinner (we eat very healthy, and the only things he can't have we eat are the things toxic to him). Including a parrot with trust issues at meal time makes them feel very accepted within their flock, and you begin to notice more positive changes over time in the way they interact with you. Sadly, our boy doesn't like petting (we have has him 5 years now, and he just doesn't want to be touched), but he's still quite affectionate and interactive from "across the room". Put on some pop music, and he dances like crazy. The more you egg him on, the more he spins and hops. If you talk in a baby voice, he will make gurgling noises in reply. He LOVES stalking up and down the shower curtain rod when your showering and grunting at you. Put him on the couch, and he will come play with your hair. In all, while he may not want to be petted, he is friendly and interacts in other ways, which is a very good sign he is now acclimated to a loving home. Just be patient with your bird, encourage his streghths, and stop focusing so much on what he doesn't like. The more ways you find to interact without touching if he doesn't like that, the happier and more willing he will be to interact with you.
