I would still crack open some in the air sack. It's not as bad as it sounds. Just get something small/pointy and hard and tap on the shell untill it dints in, then peel a little bit of the shell away so you can see what's going on in there.
I would tap on the shell first see if you can hear any noise then go ahead and start cracking. At 26 days you definitely want to interveen. If they are still alive they will need some help.
1= High Floater
2= Same as 1
3= Same as 1
4= Same as 1
5= Dud- sank
6= Same as 1
7= dud- sank
sorry they are all dudes, or failed to progress to hatching (see below, excert from float test guide). Again I strongyl suggest getting them out of there before they make a mess of your bator.
The Float Test Is Simple Yet Effect Way Of Checking Egg Viability.
Eggs Are Judged By Observation With Results As Follows:
1. Sinker= Dud, Never Developed
2. High Floater (like A Fishing Bobber Without Weights) Say 45% Or More Of The Egg Above The Water Line= Dud, No Development Or Fetal Demise, Likely Rupture Of Internal Membranes Causing The Egg To Dehydrate.
3. Low Floater= Viable Egg, Development Full Term
4. Low Floater Rockin And Rollin! This Is The Live Embryo Moving Inside The Egg= Definate Viable Egg!
Once Test Results Complete Take Viable Eggs And Gently Pat Dry And Replace In Hatcher. Duds Are Best Discarded At This Time.
Personally I wouldn't be opening eggs that are most likely rotten, or starting to rot. That smell is one you never forget, but yes it's the large end of the egg.