3rd hatch bombed...thinking of upgrading thermostat?

So my adventures up til now are here....https://www.backyardchickens.com/t/906342/fully-formed-chicks-with-large-air-cells-not-hatching

I set two dozen eggs for a third attempt. My thought was to keep the temp a touch higher and see how that went. However, 105 was not really what I had in mind .

We don't have central air, we rely on a swamp cooler. One nice hot day, honey and I were both at work and the boys didn't turn the cooler on. Got home and it was 95degrees in the house, and 105 in the incubator. I candled that night and still saw movement, so thought we were good to go. But then, a few days later, we went to the coast for the day and didn't even think of the incubator....same thing happened. Plus, it's just been very difficult overall to hold temp this time. Last two times, it stayed pretty darn steady....this time I was chasing highs and lows all the time, seemed like. Over the course of the hatch, I had temps from 97-105. Pretty sure I was lucky to get the two chicks that did hatch...

Set 24 eggs
discarded 8 around day 10, they were clear or early deaths.
Had 4 fully pip and then die
Had 2 hatch and doing fine. Happily, one is female .


I'm going back and forth on doing exams of the non-piped eggs. I don't like doing them, but I had fully intended to on this batch. I'm just wondering, with the temp spikes, if exams would tell me anything useful? If anyone has a compelling argument for doing an exam, please, I'd love to hear it. I'll hold on to them until tonight.

My honey's thinking we need to step up thermostats, since we don't have good temp control in the house. He's looking at this...

http://www.eggcartons.com/The-Incredible-Incubator-Thermostat-p/fhp-ut115.htm

or this

http://incubatorwarehouse.com/plug-n-play-digital-thermostat.html

What do you folks think? Any experience with either one? I was going to hold off trying again for August and shoot for Sept, but then we'll be having cool nights and warm days and I'm afraid I'll be chasing temps again.

I've also thought about trying to find someone local with a proven incubator to see if they'll hatch a batch for me. I've mostly been incubating from my splash Ameraucana rooster's pen, and even with the broody hens haven't had good rates this year. I'm starting to wonder if it could be him? Any input on that?