Also meant to add, many things will affect an incubated hatch. I do not toss eggs unless there's an odor. Yep, smell them! Candling is difficult right before hatch. I candle twice usually, around 14 days and at lockdown. Less you mess with the eggs more will hatch. After due date I am really watching. I remove any hatched birds every 24 hours, wet more sponges and replace them. Babies get "shrink wrapped" if you open the bator during pip or if the humidity is too low. Eggs 5 days past the due date should be candled, and tossed if there is no movement or sign of pipping.