Awww...this is tough...I know!
Franklin was about the same age when his bitey phase hit...although he wasn't much of a biter when he was out playing with us, it was more when he was coming out of his cage.
He'd be all excited to come out and play, we'd open his cage door, he'd usually already be there ready to come out, we'd put our finger up to have him step up, he'd act like he was going to, sometimes even start to step up and WHAM! He'd nail our finger HARD...then take off up to the top of his cage!
The first few times it happened, we didn't think much of it and it didn't happen every time we were getting him out...but within a couple weeks, my finger was bruised and sore! He was beginning to lunge at us, then run to the top of the cage, where HE played "keep away" ...gggrrrrr.....I was getting jumpy because...crap...it HURT! I knew I had to do SOMETHING! Thing was...after a few moments on his cage, he decided he wanted to be with us and we could then go get him and he'd be MOSTLY really good using us for his jungle gym.
Anyway, one day, I decided that if he couldn't come out nice, he wasn't coming out at all. Period.
I walked to his cage, did all my "Hey Frankie" talk asked him if he wanted to come out, which, of course he did! I opened the door and the second he decided to bite I said "Frankie, no bite" and shut his cage door and walked away. 10 minutes later, or so...I went back to his cage...same thing...you want to come out, started to open the cage door, he ran over and tried to bite me as I was opening the door, so I just left it shut, told him "No Bite" and walked away.
Later I came back and tried again, each time I'd tell him Frankie, No Bite.
3 days...it was 3 days...I was able to open the cage door, he sat there...I offered my finger...he sat there...I talked to him in all my birdie baby talk I do...all the while holding my finger in front of him...he very cautiously put ONE foot on my finger and I praised him...GOOOD BOY! Be nice...Come on, it's ok...come out and let's play!...he very cautiously lowered his beak to my finger...I was nervous...because this was typically when he'd suddenly lash out with a stout bite and run off...but he just lightly rubbed his beak over my finger...testing it...I kept talking to him and reassuring him he was a good boy...believe it or not, it took about 10 minutes...then he stepped up on my finger with the other foot...I immediately said GOOOD BOY! Frankie...what a good boy!! And he raised up and puffed up his chest all proud of himself...and from that day forward we didn't have anymore trouble getting him out of his cage.
Don't get me wrong...those 3 days...I didn't just ignore him...I still talked to him like I always would, he still got fed as he always did, his cage cleaned...etc...he just didn't get to come OUT for playtime...until he could be nice.
As far as the biting while being OUT with us...yes, that happened to, but not as much...however, if he started to get "bitey" with us when out playing...we'd grab his beak between our thumb and index finger and hold it, look him right in the eye and say Frankieeee....nooo bite in our "warning" tone.
Then we'd try to redirect him with a toy, apple slice, carrot stick, chunk of broccoli, something he could sink his beak into and play with.
And the best advice...no matter what method you choose to try and curb the biting...just make sure you are CONSISTENT! You'll have the best results that way.
Good luck and keep us posted
Toni