I been raising show birds for 40+ years and never heard "lock down". If it is what I think it means: it is the last couple of days of incubating eggs. For 40 years I have been hatching eggs and the only thing that I do differently is, the last day or so I try not to turn the eggs and I make sure there is water in the incubator. At times I have had many different hatch dates in the incubator and the eggs are all mixed togather with the hatch date written on the egg. I have never had a problem. If the egg is fertile it will hatch[there are very few exceptions]. I have read many posts that make this "lock down" seem so critical. It is not rocket science-------if a chicken can do it, it can't be all that hard. Thanks for any input.