I have been trying to hatch in my homemade incubator and am having problems. I first thought it might be from low humidity but this time I've kept the humidity around 50%. The problem I am having is that they egg develops to a certain point and then stops. There has not been a temp spike or outage. The chick covers approximately a third of the egg and when I open it it is completely dried, actually looks like it was cooked or something. I thought there may not be enough ventilation so I left the door on the bottom cracked open a little. Is ventilation the culprit? I did hatch 3 a couple months ago from my own eggs but nothing since which have been shipped eggs.I know shipped eggs are hard to hatch but there has to be something incorrect in my bator for them to grow to this point and cook. I got my design from https://www.backyardchickens.com/web/viewblog.php?id=52303-my-homemade-incubator Mine is not as nice but the concept is the same. Thanks for your help.