No,It's not marek's, Some chicks aren't meant to hatch due to whatever.Any time you help a chick hatch it usually don't make it. You know the saying only the strong survie. Private flock it's not necessary. No, No,........
First problem, It shouldn't take 3 or 4 nights to do it. Make sure it plenty dark enough.I did my rooster that way. Second problem, Put a single nest box on the ground with the golf balls get her use to using it then take it away.
Keeping the feeder full. One chicken can eat a quarter pound of food a day.So it takes alot of food. Feeding them out right every day and missing the same time every time can cause stress which could hurt egg production.
Merc, you have to have them on top of the eggs to get accurate reading. I like digital better. Walmart has a nice one that measures both temp, and humidity for $6.47 I used 3 of them this year with 97 to 100% hatch.
Most hatches are 50/50. Feather sexing don't work to good unless they are bred that way. Only way to tell is by popping out their sex organs in their bottoms. But there again to have to be trained what to look for. The 100% way to tell is after they are 4 weeks or older.