Assuming the crank is out and the head is off, a chunk of 2x and a lump hammer. If the crank is still in, maybe try rocking either the fly wheel, or the whole tractor in gear? If you have a junk starter, you might want to take a page from KOO:

https://www.kingofobsolete.ca/KING%27S_BAR_STARTER_WEBPAGE.html

Last edited by GLyford; 05/27/2019 05:27 AM.