Before you grab the drill, I would suggest patience and repeated applications of a GOOD penetrating oil and repeated heating with a screwdriver or copper rod to localize the heat. If you can find some Cabots TASGON, try that. It is by far the best penetrating oil I have ever used, but the EPA banned it in the 1980's because it contained creosote. It sometimes takes weeks for the oil to creep down into corroded threads. Good Luck, let us know how you make out.

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