Wow that is way too low that is what you put hatched chicks at eggs should be 100-101.5
How long after due date? - Page 2
A real concern would be that the chicks may run out of nutrients while developing. By now, the yokes may have been absorbed. When I had my late hatch due to temperature loss during the storm, when the chicks did hatch, they were starving and eagerly ate as soon as they dried off.
Good luck! I always candle at lockdown and sit tight for at least 4-5 days. I just had a rough hatch that dragged out for 5 days! The incubator got left open for a day, and atop that, the eggs were being collected from a very very cold coop. I was collecting 3-4 times a day, hoping the eggs weren't getting too cold before coming inside, so I'm sure that didn't help.
I waited 3 days, took the hatched chicks out, and chanced a candle. This was my styrofoam LG incubator with the plastic viewing windows, so I just popped a window out and snatched an egg quickly, replacing the window to try and preserve humidity. I candled each egg this way, removed the obviously dead ones, put the 'not sure' ones in one corner, and the 'definitely alive' ones in another corner. I waited another 2 days. All of the 'definitely alive' eggs hatched in the first 36 hours, and another day later 2 surprised me from the 'not sure' egg cluster. I whisked them out of the now very smelly incubator and got everyone eating and drinking. I lost 3 from the whole hatch due to weakness; 2 were trampled, and the 3rd was the very last one to hatch and just didn't have any umph left. But everyone else was goin' strong, a total of 20-odd chicks.
Hope that helps :)