hey A.J., still no improvement with Apple. Zeke really did get nippy, first from inside his cage, but I was not at all the informed bird owner you are.
I think I started it because I would just open his cage door and allow him out then I was told to never do that and if he doesn't want to come out force him out -- big mistake. Now, I go to the cage, coo talking to him and ask if he wants out, if he does he will step up, if not I can just tell and I close the door. When he is out and I think there may be an issue I always have an almond piece to give him as he is stepping up. He will bite/beak unknown people at the step up because he doesn't trust the "perch" is steady but with me he knows it will not waver. When out of the cage I always have some sort of bead toy to almost give him as a teething ring. I've learned my best method is to avoid the bite at all costs, from little to big. It is hard to not reinforce that bite, birds like negative reinforcement too. And dang a GCC's bite hurts like the dickens.
When Zeke is on my back or somewhere he doesn't want to leave that can be an issue because I have to fight not getting too aggravated. If I have a jacket on I just remove it. But without someone around to help and he is being ill-mannered I can be in a pickle. Again, the treat can be the lifesaver. I used to express my aggravation and get frustrated, NOT the way to be with the birdies I have finally learned. None of my birds react as well to me taking a few breaths and centering myself like Zeke does. I can feel him relaxing, too.
Good luck, it does take some figuring out and a lot of trials and errors but it is worth it when you work through it. My daughter's feelings have been hurt by Zeke biting and she won't even try anymore.
Oh, Zeke loves cheerios, too. I save them as a treat, easy, handy (messy) treats.