Float testing them should not harm the egg unless there is a pip. Please switch the eggs to lay flat on their sides. The chick is positioning itself to hatch, It is absorbing the yolk and turning so it can internally pip then fully hatch. PLEASE turn them on their sides, I have lost a total of 65 eggs in the past couple of tries. I have never heard of jelly in an egg. It could be a "ticking time bomb" That means it could explode. I wouldn't worry too much about that. Just set your egg on the side and don't touch it. If there is a blood ring that indicates that it has passed. Don't be worried about the chick passing, It happens. Yes its heartbreaking but It was bound to happen. You cant prevent it. If you do everything right it should be aye ok. Sometimes it just doesn't work. They die naturally.so basically it had a perfect air cell till yesterday when i candled it..i did not turn them after day 18 but now after i saw the air cell i have kept the broad part of the egg on the top and the narrow end on the bottom being upright..wont the water candling make water enter the egg?..already it has some some of jelly floating in the saddle part of the air cell..im concerned if it has died ..