Once again diving into an area I don't know enough about, I've pulled the cylinder off the Lister to see if there's something wrong with the piston (I was not getting compression)
Here it is cleaned up a bit, basically the oil wiped off, but still attached:
Here it is in the sun, after I cleaned it up as best I could. I hope by cleaning it, I didn't mess anything up. All the rings seem to be working well.
Here's the cylinder, that doesn't seem to look that bad: