Thanks to this this blog entry I was able to fix a Keurig Mini coffee maker, after repeated calls to the customer service did nothing but cause aggravation. It was only making a third of a cup.
Long story short, unplug, empty the water, shove sewing needle (or paper clip) up into the Keurig needle that dispenses the hot water, Jiggle it around, then descale with vinegar, to get all the coffee grounds out of the system.
Science! And thanks to that blogger linked to. Comments are closed or I would have thanked them personally on the blog.
Thanks internet, and if this helps one Keurig owner, my work here is done.
Also, YouTube has a bunch of videos of different fixes. This one is close to the money for the fix. Try at your own risk. None of this is recommended by Keurig.