Yes I have had this happen before. Get the humidity as high as you can. Make sure the fan is off, if you have a forced air incubator. Wrap it in a damp paper towel. When you see that the veins have dried out and it hasn't hatched yet and it's still breathing. Remove only the part of the shell that will free his head. Then put it back in the bator and hope that it can kick the rest of the shell off. This can take up to 8-10 hrs. depending on how long it takes the veins to dry out.