the guy said he ran it low on oil and the crank bearing burned up. its free right now but he said once it goes under load give it 5 minutes and it just stops. they have almost a sideways articulation to them, its pretty cool. when i get the 310 going im gonna have my dad tow the homesteader around so i can feel what its like.
I had a Briggs 10 that would do that. It ended up being a valve shellacking up and sticking when it got hot. You might try running it and see if that's the problem. You can take the valve out and clean it & take a drill bit the right size and clean out the guide by hand. Don't use a drill.