Now that the piston is somewhat loose time to try and pull off the iron cylinder. This was impossible by hand in my case as the cylinder walls were a tad rusty. You want to pull the cylinder up and push the pistons down and out. I found a perfect solution... not one big hammer but TWO! I used the brass one as the object to place in the cylinder in order to provide a nice big target to strike with the big steel hammer. This worked great. To get the piston completely free and out you need to elevate the cylinder a bit because the intended stroke of the piston does not push it down to the bottom of the cylinder. So if you just leave the cylinder attached and start slamming the piston it will be at the bottom of its stroke and you're just beating pointlessly on the crank.
So find some wooden blocks of some sort to place under the cylinder to keep it up off of the engine cases. Use larger ones once you start making progress. And just to save yourself some time get some wood and have a saw ready to cut the appropriately sized blocks. I was in a hurry so stopping to take pictures was painful enough. The blocks need to be shorter but not too long to get a good fit.
I had to really hit mine hard, really hard just to move it and it took a lonnng time.
I highly recommend filling both cylinders with some sort of "break-free / parts lubricator" solution and leaving it overnight. I had plenty in mine but if I let it sit for a day or two it would have worked better I'm sure. If you can spray some WD-40 or something underneath the pistons with the straw. There might be some exposed cylinder wall under the piston if you can wiggle the extension tube under the cylinder in order to get some spray around it.