I have 10 blue slate turkey eggs in the incubator. Since this is my first time hatching anything, I am very unsure as to what is supposed to be happening. I made a candling rig out of a spare brooder lamp, a 40w lightbulb and a piece of cardboard with a hole in it. I have used this setup a few times and have looked at all my eggs... I can see the air bubble at one end, then it is completely dark until the tip where I can see light through the egg. I have not seen anything else. Is the big dark area the yolk and have all my eggs failed to start? Should I crack one open and take a look?