In addition, all I can suggest at this late stage is to turn up the heat on your incubator. My guess, and that is all it is, is that your incubator was around 1.5 degrees to low. It may help. Whatever you do there are less chances of successful healthy chicks hatching.
Even in the most...
Yes I agree Amy. Heat before humidity will be the defining feature for a bad hatch especially if the hatch is late. As Amy has suggested purchase a couple of extra good quality thermometers and use them to regulate and check.
You will more than likely find that the temperature in the incubator...
Is your incubator fan assisted or still air? If it is a still air incubator, was the thermometer just slightly above the eggs? Or is it a digital incubator?
Humidity sounds right if the hygrometer is accurate.
It is late now for successful hatches I'm afraid. Was the chick in the egg you...