On day 18 I raised the humidity to 65%, and it has maintained that until today. It is now day 20, and about 1/4 of the chicks have started pipping, but the humidity has dropped to 55% during the past few hours and none of the chicks are making progress, and I am worried that they are sticking. I have considered quickly opening the incubator to add more water, but I am very hesitant to do that. What should I do?