Try working it out of the split first.
I don't see how he's eating very well, it looks like the hardened food (I assume) is caked up enough to where he can't close his beak.
Does he eat wet mash?
What does the inside of his beak look like?
You may have to work on it in stages. Apply 1 drop of Peroxide, then remove a small amount with an Orange Stick (cuticle stick).
How long has it been like this?