On used Keurigs from Goodwill, that would not pump anything. I have had to remove the water reservoir and use an air compressor with a blow nozzle and a rag wrapped around the nozzle and blow a shot of air through the inlet screen. Just blow a second or two. Do not blow very long or you will blow some hoses off inside. You will see a lot of milky white substance come out the nozzle.
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