I have two 3.5 week old chicks in my brooder right now who came from badly crushed eggs. Both were damaged badly on the pointy end 4 days from their hatch date. I had 5 eggs damaged when the lid flew off of my Brinsea while moving it for lock down. It had never failed before and I traced the problem to the manual turner I had installed and used for the first time.Whoo hoo, pleasant surprise tonight. A few days ago when candling eggs, I accidentally dropped one, nearly crushing the end where the air was. I was heartbroken, but thought.. well if the membrane is still in tact, it still might hatch. Last night I locked the incubator down for the final 3 days without rotation. I was using my little flashlight to peer inside the incubator when the egg with the damaged egg started moving. Baby inside is still alive and wiggling about!
Two eggs were doa, three still showed movement. I spackled them with candle wax and kept a real close watch on them. One chick expired the next day leaving the two that hatched with a bit of assistance as they were trying to peck through some of the candle wax, but the chicks are living proof that they can survive a damaged shell and hatch.