Here is how to do it.
Mount the shock in a vice
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Here are the tools needed. 1. A strong scraper 2.) an automotive grade tubing spreader 3.) A 17mm wrench
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Pry the base from the mount
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Slip in the tubing spreader
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Spread the mount from the base and locate the two flat sides.
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Slip the 17mm open end wrench onto the flat sides of the shock mount base
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Insert an 1/2 "extension bar through the top of the shock mount-make sure to remove the rubber bushings first.
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With the top mount off, you will see a stud with a screw slot.
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The spring tension in very little. With a flat screwdriver screw the stud in until the the spring is released . Secure the wrench on the nut if the suud does not loosen easily . Sometimes the nuts are rusted bad and you may not be able to get them loose. Invert the assembly into a phosphoric acid bath or penetrating lube to help break the rust.
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Once the spring is removed the base is released. Keep in mind that once in a while you can't get the assemble apart. So sometimes one fails.