Disassembly of the Ultimaker 2+ feeder

For instructions for the original Ultimaker2 feeder, go here

Cleaning of the feeder may be necessary if for example the filament has been ground down by feeder wheel. It's important to make sure the knurling of the feeder wheel is not clogged up with plastic as that will reduce grip and might cause the feeder to grind again.

Sometimes it is enough to blow sharply into the hole at the front of the feeder, but to make sure it might be a good idea to open it up.

Start by setting the feeder pressure to its lowest setting by inserting an allen key in the small hole next to where the bowden tube connects to the feeder and turning the screw clock wise. The feeder pressure is lowest when the little white indicator is at the top.

This isn't strictly necessary but makes it easier to take the casing apart as there is less pressure on the spring.

Next you will remove the bowden tube by removing the blue horse shoe clip and then pushing down on the white coupler. Make sure it's all the way down where the arrow is pointing. While holding the coupler down, pull the bowden tube out.   
Now unscrew the four screws in the corners of the feeder. If you hear a faint rattle from inside the feeder when you remove a screw the nut for the screw has unfortuntately come loose. More on that later.

The front part of the feeder is now free to be removed but it might take a bit of wiggling. Grab the front part of the feeder and pull while wiggling back and forth. The thing that is holding things in place is the metal part in the center which is held in by friction.

If all goes well, this is what you will be left with.   
From here it's just a matter of blowing/brushing things clean and re-assemble.

However, a couple of things might happen that means you have to remove the back part as well. One of the nuts might have come loose so that the screw cannot be tightened again. Or the round metal feeder wheel might have come off with the front of the feeder which means that the large gear hidden behind the feeder might have dropped down.

In this picture you can see how the gear has become misaligned. The easiest way to fix it is to simply remove the last part of the feeder as well.   
As you can see here the feeder wheel has a flat side which slots into the gear. Trying to get that to line up without taking the feeder off completely is a bit finicky.
To remove the feeder, unscrew the last two screws on the top and bottom and the last part will be free. Take care that no nuts fall down and get lost in your carpet.
To prevent the nuts from falling out again you can put a small dab of glue on the side of them. Just make sure you don't get glue on the threads.
Since you've now taken the feeder apart completely there's a good chance that some pieces might have fallen out, or maybe you were just curious and ripped everything apart to get a closer look. So here are all the parts of the feeder and how they go back together again.

The grommet goes into its groove with the rounded side on the outside of the feeder.
The feeder wheel is simply pushed into place.
Push the gear onto the back of the feeder wheel
Place the feeder arm into the feeder
Put the spring onto the feeder pressure indicator. If you haven't already, tighten the screw all the way in so that it's easier to put it into the feeder.
Insert the spring and indicator into position.
The little plastic piece goes here.
Line up the feeder wheel with the hole in the top cover and press the case together. Put the four screws in and tighten down. Consider putting a bit of glue on the nut to keep it in place.

Make sure you use the right screws. There are four slightly longer screws for the case and two shorter ones to attach the feeder to the printer.

Adjust the feeder pressure to the middle position. This is the starting point and works well for most filaments.
Put the bowden coupler back in place.
Finally put the feeder back on the printer, and re-attach the bowden tube.