heavily carboned new mower spark plug

I just installed a new spark plug (the recommended plug) in a Honda HRT16 lawn mower (bought at Home Depot). This plug was used once and ran OK. The second time the mower sputtered and quit. When I checked the plug, it was covered with heavy black carbon. I noticed this on two previous plugs; once last summer and once the summer prior. Is the mower running too rich? If so, how do I correct this? Any other suggestions? Thanks.
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alacat wrote:

Checked air filter? Or oil level?
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Tony Hwang wrote:

Thanks. The air filter is clean and the oil was changed Saturday. Judging from what I read a few moments ago on another mower problem thread (which I found right after posting this question), my mower is running much too richly. Still, I don't know what the fix is?
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Possibly l eaky carb float, engine flooding.
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Christopher A. Young
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The choke could be stuck on.
-rev
alacat wrote:

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Adjust carb. Replace air filter.
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Christopher A. Young
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