77horses, Are you sure your dates are right? I mean that 26 days in my book is too long. It's too bad you can't candle, but maybe you can. I used to take a bright flashlight , make like a funnel out of paper and put it over the light, and look at the egg while you hold it over the top hole.
I think at 26 days, I would pip the egg. I think the longer you wait, the higher the risk of the chick using up the air bubbl.
Again if he had temp fluctuations at the beginning it will delay the hatch. I thought I read it was below 99 some times. I keep mine at 100.9 most of the entire hatch.