ok so i am having a great time hatching for the first time however i staggered a hatch and every chick from the 2nd hatch has had problems with the embilacal ( not sure of spelling) cord/ belly button . it isnt closed shut yet and there is a little yolk left out or guts i guess, i have hatched a couple of these chicks out with hatching bc the skin in the eggs were to rubbery. all of these chicks have dided i am assuming bc their belly buttons/yolk werent obsorbed or sealed... what the heck is the problem here??? they have all pipped or popped out a section of the egg so i know they were ready to hatch... Any advice?!