The Frog started right up to drive it off the trailer this morning. The 'popping' sound was more pronounced than yesterday - more of a rattle now. When I pulled the engine cover off and listened it was quite clear; the rod bearings are gone.
For a moment I thought of holding it at 5,000 rpm 'till it explodes, but that would make quite a mess to clean up. I'm really glad that I made it through the whole day Sunday without incident because this engine is ready to send pieces through the case any moment now.
Filter and cup: