I take that back...that little partridge looks like it may have Cocci.
Do this now.
Mix up one half teaspoon of Corrid with 2 teaspoons of Corrid and give that baby 4 drops of this solution straight to the beak twice a day, in addition to have the 2 teaspoons mixed with the gallon of water as their only water in the brooder.
You have to make sure you are mixing a new batch daily, and not just filling the waterer with the old mixed up batch of Corid water.
I still think you need to move the brooder.
You could be dealing with bad stock eggs/parents.
If you have been having the same issues for months with the same eggs purchased for the same person I would no longer purchase from them.