Suggestions for assisting with guinea hatch

[Loghousemom]

I had posted this in another thread, and then it was brought to my attention that it might get more notice if it were in this section so I am going to post it here too.

I am on the last days of my guinea hatch. I had 4 hatch yesterday. I have 4 eggs remaining. Today should have been hatch day.

I removed the 4 keets this morning because my humidity was seeming to drop and I wanted to add warm water. I candled the eggs that are left since none were pipped. 3 are certainly dead, I cannot see movement that I did see at lockdown. One is moving, but possibly stuck. It has not pipped through membrane yet. I am sure I should leave it, but if I decided to try and help it hatch, what would be the best way to break through the egg shell? I know they are harder than chicken shells.

I started with 18 eggs and this has been a difficult incubation. The incubator crashed topside down about 2 1/2 weeks ago, full of 45 eggs, and the turner. Of course most of the eggs were badly broken. Many of the remaining died during the days that followed. Since the crash, the temp and humidity seem to randomly, rapidly change. I cannot tell if it is a malfunction of the incubator or thermometers. (I have 2 thermometers and both seem to read fine every time I check them, but the one digital also records high and lows. Previous to the spill it held temp very well, so possibly these temp swings have caused the additional deaths since lockdown.)

I will likely wait until tomorrow to do anything, because I don't like to make a habit of assisting at hatching time, but I feel like I should be prepared because this has been such a difficult hatch already, I wanted to giveaway fighting chance to as many of them as I could.

So, the question is, does anyone have Any ideas on how to safely crack the egg and possibly save a weak keet that has not pipped internally or externally?