It is a trivial job. Simply pushing down on the extractor and, holding your finger on the end, slowly let it come out, along with the spring and plunger. The spring is under some tension, so be sure to let it come out slowly. The new extractor is simply pushed back in after the spring and plunger. I believe clear instructions come with the extractor. I replaced mine without any issue (and I'm a klutz at these things).

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S&W SW22 Victory