Background: over the course of three-four months, we lost half of our chicken flock; on average about one a week. We have now gone a month without any more losses. Our chickens are free range, and we reinforced as best as possible because they are free range. So to replenish the flock, incubation! 10/5: Day one, 8 eggs into a Brinsea incubator, with attached humidifier and auto-turn. Temperature set at 99.4 degrees Fahrenheit and RH% at 45. Cool down was set at one hour, by previous users. 10/6: Day two, four eggs added, to make an even 12. 10/22: Day eighteen, about to go on lock down. I candled four-five days prior, and everything but two eggs looked good, air sacs, veins, etc. Raised the RH to 65% and turned the auto-turn off. 10/25: Day 21, "hatch day". Nada happening 10/26: Day 22, nothing happening. 10/27: Day 23. Nothing happening, but noticed a smell coming from thebincubator, so took the lid off, noticed a pip on the backside of an egg, so quickly put the lid back on. By 4pm, first egg was hatched. Few hours later, another egg had pipped externally. 10/28: Day 24. #2 hatched by morning, and #3 hatched by evening. A fourth egg was pipping externally. 10/29: Day 25. #4 hatched overnight. By afternoon, I moved the hatchlings to a brooder. I float tested the remaining 8 eggs, and all floated with only 10-15% above the water. I then candled them, and only three were dark inside, and I could see a form, though I could not detect movement, I put them back in the incubator. Five duds: I eggtopsied, and two were not fertile. One showed a few days development, one showed perhaps a week of development, and the third appeared to be a fully formed chick that had been squished between two air sacs. It's beak was under the wing, like it was ready to pip, then died. As far as I know, there weren't major fluctuations in temperature or humidity (aside from candling day). I would check the readings multiple times a day, and make sure the water reservoir had ample water. The only ones I saw were +/- a tenth of a degree of % for RH and +/- 1 degree in temperature, which I assume was from the outside temperature. My question(s) : Do I have the cool off period, wrong? Should I calibrate the temperature and RH, to make sure they are accurate ? Because at this point, 4/12 successful hatches, is a bit disappointing. I would like to incubate more, but want to see if I need to fix a problem, that I am not seeing. I am thinking of waiting 24-48 more hours on the three eggs that went back into the incubator, but I don't have my hopes up. Today is Day 25. Any help would be appreciated. Thank you.