You're one of the lucky ones Rich. I have never seen them not crack st the hub. My customers who have them complain all the time and I have sold every metal one with ease
My plastic grinder hasn't cracked yet either, but I'm also in the more occasional use and not overloaded categories. No argument that if I have to replace it that it'll be a metal replacement.
Before you grind, cut the meat into 1" cubes, arrange it in one layer on a sheet pan and put it into the freezer for about an hour, or until it gets a frozen crust, but is still somewhat pliable -- semi-frozen.
I've seen this advice many times before and I've always wondered, who besides the people who do cooking shows on TV have enough room in their freezer for a sheet pan full of 1" meat cubes? I've got a separate upright freezer and I still couldn't get a pan of meat in there or the freezer on the refrigerator.