I'm 99.9% sure it was a loose connection in the forks that caused this. I've seen it before, but not to this extent.
If you look at the hole in the bottom box (closeup picture) you can see what's left of the two line lugs. Usually the POCO uses the left side lugs for line, then it goes up the stabs and through the meter, and back down the other stabs to the load lugs.
Once we get into this job in a couple of days I'll know more of what actually happened. I've also got old parts for these meters, so I'll include some pictures of what it should look like.
CT, that is snow you see.