Trying to improve hatch rates

I've been incubating for some time now with mixed success.  The results are all over, but I can generally point to inconsistencies along the way that were probably the reasons for poor hatches.

I am on the cusp of completing a hatch in which I think I did most everything right.  I have two incubators.  One with a turner that I run the first 18 days at just about 45% humidity (by my hygrometer).  The other incubator is used for the last 3 day "lockdown" and runs about 65-70% humidity (before the first one hatches - it's hard to keep steady once they start hatching).  I've had both of these incubators for a while and have the temperatures set where I don't have to adjust them anymore.  Both incubators are inside the house in a room where the temperature fluctuates at most about 4 degrees between day and night.

With that set up, I started with 21 eggs that are a cross between a Barred Plymouth Rock rooster and 4 White Leghorn hens.  At 7 days, I had 1 egg that was either infertile or never took off.  At 18 days, I removed 3 eggs that had quit early.  That left 17 eggs going into the final stretch on lockdown.  They were due on 8/4 and started hatching that day.  At the end of the day on 8/5, I took the first 5 hatches (who had been in more than 24 hours) and placed them in a brooder.  After carefully taking them out (leaving the lid in place and just cracking it enough to remove them), I poured hot water into one of the reservoirs so that the humidity remained high through the whole event except for the moments I was taking the chicks out.

Today, after I got home from work, I found another 5 had hatched (for a total of 7 still in the incubator), however one had died.  It had a bloody bottom.  As I looked closer, the other 6 chicks had bloody beaks.  No doubt, they were just pecking at the blood, but I don't know if they killed the chick or if whatever happened during the hatch ultimately did it.  Regardless, my number stands at a total of 12 hatched (11 surviving), 1 chick that has pipped but may be dead in the shell, and 4 eggs with no pips.

If that number stands, I've got a 57% hatch rate with 52% surviving.

Any tips to get that number up?

It always seems to me that once a few chicks have hatched, they start playing bumper cars with all the other eggs.  A few hatches ago, I had 5 that had pipped (2 of which had zipped quite a bit) that died in the shell.  I assumed that somewhere in the shuffle, the other chicks flailing around had somehow caused the deaths.

Can I (should I) put the eggs in something where they can't be rolled around (and into each other)?  Suggestions?

Thanks!

I am more or less following the dry incubation method - at least what I've read of it.  Bill Worrell suggested an in house humidity of 50% and then adding no water to the incubator.

In the first incubator, I add no water, so the humidity is a factor of what is naturally occurring inside the house.  I didn't trust my hygrometers so much, so I actually weighed a batch of eggs to make sure they were losing close to 13% of their weight by day 18.  They were right in line.  I figured that was a much more accurate indicator than cheap hygrometers that may or may not be accurate.

In addition to no water, the "incubating incubator" (a foam type) has both red plugs open for maximum air flow - plenty of oxygen.  The incubator was originally a still air model, but I added a 12v computer fan running on a 5v transformer (so it is more gently circulating the air).  It has an automatic turner so I don't have to open it all the time.  Typically, I set a dozen +/- eggs a week.  At that time, I candle the ones I set in the previous two weeks culling any that have quit or are non-starters.  I only open the incubator one other time in a given week, and that is to take the 18-day eggs out, candle them, and then set them in the "hatching incubator"

The hatching incubator is a Farm Innovations model much like the Little Giant except it has a plastic shell around the foam. It has a built in fan.  On day 18, I will have this freshly cleaned incubator up to temp and humidity (65-70%).  I will set the eggs at the end of the day and lock it down.  I have the water reservoirs fairly full in order to make the 5 day adventure without having to add water.  I use the red plugs to regulate the humidity through the hatch.  Generally, they're both in until the first ones start to hatch and it keeps the 65-70% up until that point.

I've had chicks "drown" and had them dry and stick to the shell unable to get out, so I know the signs of each - and have had a lot of things in between.  It seems when everything is right, the chicks are pretty quick from pip to zip (hours rather than a day or so), and kick right out of the shell once zipped.  That seems to tell me that I've got some things right.

What puzzles me is that the 11 surviving chicks are very hardy and hatched like a textbook.  Why then are there still 5 eggs that were moving around and developing on day 18 that now seem to be going on the mortality list.

Another thing, when I see folks write about their hatch rates, are they talking from day 1 or from day 18?  Bill Worrell claims to consistently hatch over 90% with some 100% hatches under his belt.  I can see that from day 18 (I just had a 70% in that case), but how can you achieve 37 hatches out of a full 41 egg batch in one of these foam incubators?  You'll have at least 4 that don't start of quit it would seem to me.  That leaves you at least the last two weeks where everything has to work perfectly.

On the other hand, I don't understand why 5 of my 17 eggs placed on day 18 haven't hatched when everyone else seems to have enjoyed ideal circumstances...

They are my own hens/eggs.  They are free range by any number of definitions, but they primarily have an enclosed area in which to forage by day and have free choice Purina Layena (TM) and fresh water available at any time.  Of these, I select the best eggs and never place anything that is porous, cracked, or misshapen.

What is unusual to me is the activity at day 18, then never hatch.

I've seen some folks who look like they are hatching their eggs standing up in a carton.

I have thought of doing that only to keep the hatching chicks from rolling eggs around into each other.  I have read all the cautionary tales of keeping them on lockdown and handling them carefully, but then I see drunken chicks roll them from one side of the incubator to the other hitting every other egg along the way.

Is there a problem keeping them vertical (air sac up, of course) for hatching?