Wish I still had a pic of it but my old 1964 M&M Chuck & Duck. What a work horse!!! Had her screaming at full bore put in a 6 inch chunk of maple when I heard this loud, and I mean LOUD BANG! Whole chipper came about 2 feet off the ground with the drum and engine stopped dead.
Turned out to be a 1 inch solid steel rod embedded in the maple. Bent the anvils down and out adn blew out the one knife. No harm to the engine or rest of the unit.
Ended up getting the blue wrench out, heated up the anvil support (large channel iron) till it went cherry red, then jacked it back into place. Had to do it several times but we got her back and functional!