Verifying the accuracy of temp and humidity readings is critically important for good hatches. Unabsorbed yolks also suggest temperatures running low, and too-large chicks can be a sign the humidity's too high. I hatch a lot of eggs, and 60% humidity for chicken eggs until lockdown sounds too high. With experience, I find drier conditions produce the best results. This article may be helpful.I got another temp reader/ humidity. I'm going to test what it says tonight. I had a couple chicks come out and still have yolk to dissolve. But I had some chick that never made it out of the egg and some seemed big for the shell.