I wouldn't worry about the eggs being at 104 for just a few minutes. I was recently fighting with my incubator trying to stabilize temps, and it hit 104 more than once (one time for at least a half hour if not longer), and got down to 90 more than once. 10 out of 11 chicks hatched. They are...
I've been using an ecoglow brooder, and that allows the chicks a normal day/night cycle like your heater pad hen will. I believe it allows the transition from heat to no heat to be easier on the chicks. When I used a heat lamp, the chicks would get very agitated and stressed the first few...