I have an old JD 420 2 cylinder that has started missing badly and running rough. Last spring I had similar issues and I thought it was electronic related. I replaced the spark plugs, wires, condenser and points, nothing helped. I ended up taking out the fitting in the bottom of the gas tank and it was plugged with junk. Once that was cleaned out, it ran great the rest of the summer. So far this year it was running great until this week when I hooked up the disk to run over the garden. It ran good for a couple of turns and then it started missing and would barely pull its self. Last night I drained the gas tank and removed the fitting in the bottom of the tank again. I also removed the carburetor. I took everything apart and cleaned with gas and carb cleaner. I put it back together and filled the tank with new gas. It started right up, but I have the same issue. I?m not much of a mechanic, so any advice would be helpful. Thanks