important crested gecko - long incubation question

I have read every care sheet available and have spoken to countless breeders on the phone, through, e-mail, and at expos.

My gecko eggs are driving me nuts! today is day 82 for two of my eggs. My other sets of eggs have a while before I can be concerned about them. I had no problem hatching leopard geckos using a home made incubator. I have had a few failed attempts with my geckos and they are driving me crazy because each time i've been doing what others have suggested and done themselves. I tried room temp, I tried my home made incubator, and now I have an actual incubator that I got from tractor supply. The hatchlings develop fine and then don't hatch. They take a very very long time to incubate and I don't know why they are not hatching. I had 2 eggs that I kept at 70 degrees for over 140 days and they never hatched nor did they show any signs of molding until all of a sudden the moisture level jumped drastically and they burst. This happened more than once each with a very long incubation period.

With the two eggs that are at day 82, I have them in a little giant incubator set at 78-80 degrees. They seem to be developing alright but they should have hatched 20 days ago at those temps. They are not showing any signs of molding or death. The hatchlings are too big to candle the eggs now. The eggs are nice and white and full and round. I'm hoping that maybe they're just taking their time but have others had late hatchlings at these temps? Every care sheet and everyone I've spoken to have said that at 78-80 degrees they should hatch about 60-65 days.

Like I said, I've hatched leopards before with a home made incubator with no problems. I know how to mix the substrate just fine and if it weren't than the eggs wouldn't make it to term anyway and would have died sooner.

Any ideas what might be happening?

PLEASE LET ME KNOW! I'm getting so disheartened and frustrated.