This is my second hatch and three ducklings have already hatched and running around the incubator! One egg has zipped but isn't shaking/moving or doing anything whatsoever. It has been like this for a few hours. Another egg has one crack and is shaking nonstop. I'm very worried about the egg that isn't moving and hasnt moved for a while. Is it dead? How do I know if its dead? Should I help it?