Strange Nanday behavior

Question
On July 5, 2007, I took in a rescued Nanday conure.  The young woman who had "him" seemed like a nice young lady who did not know how to deal with this bird.  I have two rescued Mealy Amazons that were in really terrible shape and now wonderful companions, so I felt that I would be able to handle a conure with no problem. However, I am completely unfamiliar with conures as my experience lies with Amazons, Meyers, and Cockatoos.  Stewart is a VERY frightened bird, he is quarantined in my back office and I spend quite time with him working on the computer.  When I enter the room he squawks and stretches his wings so I know he is please with my appearance in the room.  However, though he appears to want my attention something is holding him back. He will not take any food from me through the cage and when he is out he will grab the food and toss it rather violently away. He also repeatedly rubs his face on his perch and picks at his nails, it seems almost compulsive.  He is a sunflower addict and, having had a cockatoo that was one as well, I am slowly reducing his intake.  He will not eat any fresh food presented to him. I understand that conures are very social and I am anxiously awaiting the end of quarantine in hopes that being around the amazons, cockatiel and budgies will give him some confidence.  In the mean time, do you have any insight on his behavior or any suggestions for things I might try with this particular species?

Answer
Don't second guess yourself. It sounds like you know what you're doing and while there are nuances of difference among parrots, the most important thing is that they are treated with patience and respect.
 You've got quite a chore ahead of you to get him off his junk food diet, but it can be done.  
 What's holding him back from interacting with you is his history. He has little reason to trust much right now, so hang in there and persist. Remember, he's also hearing the other birds and has no real clue as to what's going on outside of his quarentine.
 We often avoid this by having our avian vet do a full check up within a week of our taking in any bird. We include a genetic disease screening which also confirms their sex. Results are generally back within a week of being done - and with clearance - we start integrating up to a month sooner than we would be doing so otherwise.
 And the biggest drawback of a quarentine is that these birds almost never show signs of genetic disease in this period of time (and may just be carriers).
 When it comes to teaching him proper eating, the thing working in your favor is that these birds (all parrots) tend to imitate not only sounds, but actions. We've gotten many rescues to try new foods by eating the foods in front of them and then offering some.  One of our girls will actually make sounds like she's loving it, never tasted anything quite so delicious "Mmm, ohhhhh" - it's too funny!
 He's going to learn by watching the other birds too.

Withdraw his sunflowers just a bit at a time rather than all at once so he doesn't stress out any more than he is.

 I've got more info you might be able to use at my site so take a look and let me know how it goes.  I'm here (or there) to follow along with you on this.
  And by the way, thank you for saving his life.

www.4AnimalCare.org