I bought a JD318 about 6 months ago. I stripped it down to the frame and cleaned it from top to bottom. The previous owner never fixed the oil leak it had oil, grass, and anything else you could think of was caked all around the engine. The belly screen was caked so bad with stuff I had to use a wire brush and scrapper to get the gunk off. I cleaned engine the best I could "I'm not a small engine mechanic" taking off parts I knew I could get back on myself. Sorry to be so long winded. I spent two weeks almost every night gettin her back together replaced fuel lines, plugs, plug wires, throttle cable, choke cable, and engine bolts. I also found the oil leak, it was the gasket behind the oil filter, so I replaced it cleaned the carb. and resealed the intake manifold. After putting it all back together the engine ran 100% better. The only issue is when pushing snow this winter it would bog down when pushing a heavy load. I was moving some dirt yesterday and it bogs to the point where it wants to stall. I'm not sure what to do next. I've been told to get someone to rebuild the engine or repower the tractor with different engine. Can anyone give me some advice on what to do next? I have some picks of my break down and rebuild.