I'm not much of a mechanic. Our rider will start from cold (like at the beginning of the day), you can be cutting the grass, shut it off, it'll restart...but intermittently, at the end of the day...it won't start when we go to put it away. It turns over, but doesn't seem to fire. We let it sit and cool (or clear out the carburetor of excess gas), but it still won't start. I've replaced the plugs, the wires seem to snap on tightly, we've tried different gas cans (so we don't think it's the gas). I'm thinking it has to be something either in the carburetor or in the ignition. I have no idea what to try next. Any help/suggestions will be appreciated.