If he's desperate enough to seek out food between the grates then I would suggest re-portioning his pellet to seed ratio. It's a set back, but these things take time. & It sounds like he needs to become a bit more independent. It seems as though he's relying solely on getting out of his cage as entertainment. Does he have foot toys in addition to hanging ones? My Hahn's loves throwing balls around on the bottom of her cage.I have seen him on the bottom:
- looking for food: usually during the rest of the day when it happened
- waiting for me to come and open the cage this way he can go out on my shoulder or on someone else.