If you're new to incubating, don't pitch any egg unless it actually smells rotten! If you're seeing dark blobs in some eggs then those ones are most likely the good ones and you're not seeing veins because the shells are thick or dark, or just because you're not quite sure exactly what you're looking for/at. (I know the first time I incubated, I candled at 7 days and cause I didn't really know what I was looking for, I almost didn't see the veins or the tiny black blob of the embryos!) So keep them all in and candle again just before lockdown. By then it should be obvious which eggs are doing well, cause there'll be a big air sac, and the rest of the egg will just look like a solid dark mass.
Good luck!
