How many lumens is your flashlight? I have a MagLight thats 220 lumens (I believe), I picked it up at Wally World. Its super bright, has a high beam and low beam, and I could (just barely) make out what was inside the last batch of Marans eggs I incubated. If yours are really dark, I'm not sure a candler or brighter flashlight will do you much good. Thats just the way it seems to go with chocolate eggs. I do more sniffing (for off, funky smells) than candling when I incubate them.
Good luck!