I know exactly what you mean..........
I am Kat who Pippy was telling you about, i have a 2 and a half year old grey that decided to barber, or snip his feathers on his neck, chest, back and tops of his wings last september. He did not once pluck the whole feather so was left with a fluffy area.
There had been no obvious signs of a trigger but with the help of June and his breeder, we put it down to hormones and a strong bond with me, and therefore a seperation anxiety. By looking at your pics they look just like what Max has done, not as bad thankfully for you. If Ozzie came to you like this it will be hard to determine how long he has done this for and what the trigger may have been, but here are some things you can try to help and may be even stop him from doing this again. However one thing to realise, once a plucker always a plucker
I held off taking Max to a vet as did not want to over stress him unnecessarily, this was my choice and if he had continued to the manic extent he was snipping/ barbering i may have done so. If you feel it would be helpful you may want to do this, but remember there is no cure for feather plucking, snipping or barbering
I sprayed Max several times a day even before bed ( i know under normal circumstance this is a no no but needs must), i used warm water with either cider vinegar or listerine ( 5mls to 500 mls of water), i soaked him each time. I was also given a product that was recommended as when Max picked it was a frantic almost pain relieving thing....might sound weird. The Avix soother spray has helped so very much i would recommend you get some of this if you can. He has a daily spray now, and if i am leaving him to go to work this is when i do it.
Aswell as the spraying i gave Max alot of destraction things like toys, he has a toy box and i rotate his foot toys around every day so he doesn't favour one over the other ( as part of his problem was becoming rather attached in a sexual way to a particular toy). I also play games with him, whether that is peek a boo or a training technique like shake hands and wave. All just to take his mind off the picking.
He has a good diet of veg, fruit and tidy mix. Also he has manuka honey and palm oil on toast every other day. I did increase the amount of calcium he had for a short time, then normal amounts and a boost every 6 weeks at the moment. I use Nutrobal or zolcal D. I also give him Feather-Up and have to say since using this i have seen a huge improvement in his feathers. He has now nearly 5 months on started letting his feathers grow and is leaving them alone (touch wood and fingers crossed).
Do you give Ozzie a calcium and broad spectrum vitamin supplement? Does he have out of cage time, playtime etc.? What sort of diet does he have. If you can tell us this we may be able to find a solution. But remember there is no overnight cure.
Here are some pics of Max to show you what he has been through from day one to the last pic taken today
I hope this helps in some way