Hi Jennifer,
Your parent birds are over-grooming the chick. If there is only one chick, this is more common. He should be ready to leave the box very soon and then the parents will stop this. As soon as he can be out of the box, take the box down. Otherwise the parents will try to breed again to soon. They need to be rested about 6 months before you give the box back to them and let them breed. You will need to remove the chick from the cage as soon as they have weaned him, or they will pick on him more aggressively in order to drive him away. This prevents related birds from breeding in the wild, and of course you do not want the chick to breed with one of the parents.
Thank you for asking Lafeber,
Brenda