Aw, the poor baby
I just had this very same thing happen with one of my chicks. I had a terrible hatch rate with my last batch (tried hatching using the dry method AND with pulp egg cartons-wouldn't recommend it, but) I had to help one hatch and the foot just looks different than the other-like it's swollen and boneless (for lack of a better word...).
Could you PLEASE show us a picture of your cardboard shoes? Also how you wrapped it? Would that sticky wrap (like for horses legs) work?
My chick is a few days old now and I hope that it isn't too late to fix it. What we don't do for our little babies, huh?
TIA-Good luck on mending your ducklings foot-keeping my fingers
and saying a little prayer....
Just another little thing-I've noticed that I usually get a chick like this when I have a bad hatch rate (usually have great luck).
I love the dry hatch method-had great luck the time before last when i used the turner, but I had another batch in my other incubator and only one turner, SO I just used the pulp egg cartons and tipped my LG up with a little prop and then moved it to the other side the next time. The humidity level was good, but my egg cartons were absorbing the moisture. A lot of the eggs STUCK to the carton and some had a mildewy/moldy powder on them. If anyone tries this, I highly recommend cutting a small hole in the bottom of the egg carton cups. I don't recommend this method, but if you want to try it, that's just my .02.
I did open a lot of the eggs and most of them were fully developed-it was such a shame.
I had to help another one from that same hatch because it wasn't zipping, it was just making a hole bigger and bigger. That chick's foot was just fine. I wish I could figure out what the foot thing is caused by and why is it ever only one foot?