Our Keurig Vue stopped pumping water after just a couple of months use. It would start, but you could hear it was struggling, and no water was making it into the cup (or even the coffee pack.) Note that this repair applies to the Vue machine, although it is likely the same issue can occur (and the same fix apply) with other machines.
Determined to fix this myself, I started taking it apart and quickly located the issue. I thought I would share here so others could benefit from this knowledge. The only tools needed are a toothpick, a sharp point like that on a small paring knife, a plastic thumb-tack (or a metal pick if you have one), and a Philips screwdriver. I recommend removing the water reservoir, unplugging the machine, and placing it over a towel in a place with good lighting. The towel is to prevent the small screws & washers from vanishing!
Before starting this repair, please pay careful attention to where you put your hands while working on this machine. Behind the cover we will remove are two VERY sharp blades designed to puncture the coffee pack. They would easily penetrate skin and cause serious injury.
Step 1: Remove the Cover Below the Handle
This cover is the most difficult item to remove and replace. You'll see why as we go thru this repair. First, with the handle fully-open, use your sharp pointed object to carefully pull the small plastic covers out. They slide out quite easily but it's difficult to get them started, hence the need for a very fine point. On reflection, a plastic thumb-tack would probably work better than a knife. If you do use a knife, however, please be careful! Holding the blade wrapped in a dish towel would help prevent injury, as well as keeping the spare hand on top of the machine, away from the knife.
Once you have the plugs out, note they are angled - the 'tall' end goes 'up' when you reinstall them.
Remembering that there are sharp blades below this cover (i.e. don't stick your fingers down there!), remove the two screws, being careful not to lose them, then tilt the cover backwards slightly, and it will pull up. Do not force it, once you have it tilted back, it will slide off quite easily. Getting it back on is a challenge, but we'll get to that later.
Step 2: The Offending Item
With the cover removed, the part that is causing your problem is visible. The clear hose on the left is the supply from the water heater, and feeds into the coffee pack through a rubber hose. If you look down behind that round plate, you will see the blade that feeds the water into the pack. There is another blade below this, for the water exiting the pack - you can see part of the drain system below the inlet hose in the first picture.
Break a toothpick in half, and use the sharp end to poke into the three holes in the upper blade. Again, be VERY careful working in there. You will probably feel the obstruction - dried coffee grounds - break free as you wiggle it around. Now close up the machine, plug it in, replace the water reservoir, and run just plain water into a glass, measuring cup, or light-colored cup. The machine should function normally, and you should see the debris that you removed flushed out into the container. If so, you're good to go - proceed to step () to replace the cover.
If, however, the machine still can not pump water, then you will need to either repeat the procedure, or remove the blade for cleaning.
Step 3: If at First You Don't Succeed..
This is actually an easy step, but please remember to keep you fingers away from the blades!
You're going to remove the blade assembly, which is the round plate you see behind the hoses. Remove the three screws, being careful to keep them and their washers together in a safe place. The plate is now held in place by the silicone parts you can see from the front. Is order to separate the plate from the inlet hose, you need to pull it towards the back of the machine a little, and slide your finger down to hold the hose back as you pull the plate further. Once it is released, grab the exit hose (the smaller one lower down) and now pull the plate straight back. It will release and the plate is free.
Look thru the hole from the back side (please don't poke your eye with the blade!!) This is what you should see, I'm betting you can't see thru it. Use the toothpick from the inlet side, and clean out the holes. When done, flush with water and you're ready to replace the plate.
It goes back in simply reversing the steps you took to remove it - It's hard to mess up as the pieces that the screws go into are also alignment pins for the plate. Align the plate so that those pins will go back into the holes, hold the lower hose and push the lower part sticking out of the plate into that hose, then push the main part into the inlet hose. Reinstall the screws with washers. It's worth mentioning that if you put those screws with the ones from the cover plate, they are not the same size. The ones used here are larger. At this point, test the machine with plain water again, and you should be set to reinstall the cover.
Step 4: Wrapping Up!
The cover has two "hooks" that slide over "pegs" on the coffee pack mechanism - I've highlighted one set in the first picture. The process is made difficult by the fact that the parts where the screws go have to slide "under" that frame. I can't offer much advice on how to do this as I've never been able to figure out a repeatable way to get the cover back on. You simply do the best you can to align those pegs with the hooks with the cover angled back a little. Once installed correctly, you can see the holes for the screws line up. You'll note the sides of this cover go around the handle sides. When installed correctly, there is a little bit of play before you put the screws on - the cover can be tilted back and forth a little. I've included a couple of shots of how the cover aligns with the handle sides so that you can use as a reference when reinstalling the cover.
Good luck, and please let me know if this helps you get your precious machine brewing again!