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Error 051 in a Fetco brewer signifies an open temperature probe. Probably replacing that temperature probe would cure the error message, but it seems it isn't cured by a reset.
That's the initial indication I get, of an answer to your question.
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I would recommend that, before replacing the temperature probe, you check all of its connections - if one came loose or was dirtied enough, it might register to the circuitry in the brewer, as open (when it really wasn't.)
After that, replace the temperature probe.
If you need further guidance, let me know, please. (If this finishes the case for you, a rating would be appreciated!)