Sounds like you might need to descale your machine. Crap builds up inside the boiler and prevents correct operation. If you have your manual it will describe how it is done.
Otherwise go [http://www.keurig.com/medias/K10-UCG-ENG.pdf?context=bWFzdGVyfGstY3VwLWJyZXdlcnMtdXNlci1ndWlkZXMtcGRmc3w0MDY4MDE0fGFwcGxpY2F0aW9uL3BkZnxrLWN1cC1icmV3ZXJzLXVzZXItZ3VpZGVzLXBkZnMvaDE2L2g3NS84OTU1ODk5NDQ1Mjc4LnBkZnxlYjc1MTYyN2I5ODZiNjA4ZTEzNzQxN2RjYWNlZGMxZDQ1YjM2Mjc1OGVjMGQzNDc0MjMxMmM5NTE1ZDU0NWQx|here]