In ,
micky typed:
The fence post I thought was broken off near the bottom, under ground,
turns out to be broken off just above ground level.

The post still in the ground seems to have turned into dirt.

What do you all think about using my wet-dry vac to vacuum out the
moist dirt. Will I ruin the vac? Will I ruin the foam cover inside?

When I buy a new post, what do you think about my getting one 1/2"
less in diameter? Easier to put back in the hole?.

The post is about 4 1/2 " in diameter, but interestingly, the middle
3/4 to 1 inch is still made of wood. Below ground level (to a depth
not yet known) it's not dirt yet, and in the piece of the post that
was standing above ground level, it's different from its surroundings
too.

I am not sure that I can completely picture what you have there now. But,
could you just dig out a hole down on one side of the buried post, then
maybe do the water trick to remove more dirt around the old post, then tip
the old post into the hole and pull it out from there?

Or, do the same as above, including the water part, then tie a tow rope
around the "stump" (old post), and pull it out with a vehicle. That's how I
recently removed some pretty large arborvitae tree and bush stumps -- muddy,
but definitely fun.