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Replacement parts for Whirlpool KSRG25FKSS15 REFRIGERATOR | AppliancePartsPros.com
The compressor is Item 28 in Section 12 and costs approximately $270.00.
If you click on it's picture a new page will open with more info and a Q&A section.
This is not a job for an Appliance DIYer, special tools and experience is required.
Also in most areas the tech must be certified to work on refrigeration equipment.
As long as you are sure the compressor is toast, often it makes more sense to put the dollars towards a new unit.
One thing to check is the warrant as the sealed system usually has a longer warranty than the rest of the unit.