Yeah, I took some nasty bites from Bongo when I first got him because he didn't associate me as his "buddy". He bonded with my mother VERY quickly so he is becoming her bird more than mine. I'm fine with that because I just want to make sure he is happy.
Davo, to answer your question, Bongo was abused by his previous owner. To this day he is terrified of any sort of long cylindrical objects because his owner used to hit his cage and jab him with a broom.

At first I didn't know that until I bought some new toys for him and he started growling and flipping out when I put a long chew stick near his cage.
He is much better now that he is in a home where people love him. I ended up getting him when I worked at the petstore with a friend of his owner. She told me what was happening and she didn't know what to do about it. He called the store and I talked to him and at first he basically told me to go f*** myself and he could do what ever he wanted.
I happened to be in on my day off when he was there visiting his friend so I talked to him face to face. It's amazing how much his attitude changed when he realized he was telling a 6'4" defensive lineman to go F*** himself. Long story short, we came to an agreement that I get Bongo in return for me not taking his life.