How to remove damaged faucet seat?

I am using the tapered hex tool for removing the faucet seat. I was able to remove the hot water side, but the cold water side is not coming off. I am afraid that I might have stripped the hex hole, because the tool is turning but the seat is not. I have also tried the standard allen wrenches with the same results.
I was thinking of pounding the hex tool deeper into the hole with a hammer, but I do not want to destroy the seat. The reason is, the seat is working ok for now, and the only reason I am replacing is because it is eating up the stem washers fast.
Any ideas would be appreciated. Perhaps there is a tool out there that can remove seats with a damaged hole.
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Use an extractor with a reverse-threaded taper that will dig in when you screw out the stripped seat. Tom
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use a seat resurfacing tool, it grinds / smooths the existing seat saves replacing it, under 10 bucks
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