Greetings from GoVacuum.com,
Miele canisters have 2 different types of power brushes. The first, and most popular is the Miele SEB 217, and 213 Power heads. To remove the brush, follow these instructions.
On the bottom of the power head there are 2 yellow (older models it is black) plastic screws. You can remove these screws with a phillips head, or flat head screw driver. Simply unscrew these two screws. You do NOT have to remove these screws, just unscrew them to where they are loose enough to remove the bottom plate.
Once you have unscrewed the plastic screws, simply pull the bottom plate up and off of the power brush. You will notice the belt on the left hand side of the brush. Simply pull the brush up, and un hook the belt from the brush;
Now that you have unhooked the brush from the belt, you may thoroughly clean the brush, and un wrap any hair or thread that is wrapped around the brush. You will notice on the roller brush itself there are two indentions on both sides of the brush that run the entire length of the brush. You can take a knife or scissors and run them down the brush on both indentions, which will help you remove the stubborn debris wrapped around them.
Also you'll notice on both sides of the brush that there is a yellow bearing cap on both sides of the brush. You may pull these bearing caps off, and remove any debris that is around these caps. You may also lubricate these bearings with grease or WD-40, to ensure the brushes spin fluently.
After you have cleaned the brushes and bearings, insert the brush roller back through the belt, and into the power brush. You'll notice that the bearing cap will have two sides. One side of the bearing cap has 1 groove in it, the other side has 2 grooves.
When you reinsert the brush back into the power brush, you may lower the roller brushes if the machine has been used a lot. If the roller brush is older, you will want to re insert the brush with the side that has 2 grooves facing upwards, and the side with 1 groove in it, facing down. In the first picture above, you will see that the side with 1 groove is facing upwards and is visible to the camera. The side with 2 grooves is facing down. This is because this brush is new. If your brush is older, you will want to reverse that, and have the side with 2 grooves facing upwards. When the brush is back into the power head, simply put the bottom plate back on, (IMPORTANT! Make sure that in the front of the machine the bottom plate is completely hooked onto the front of the power brush, there should NOT be any space in the front) Once you have screwed the plastic screws back into the power brush, in the front of the power head, push the bottom plate upwards to make sure there it is fastened tightly in the front.
I hope this helps you. If you have the larger, less popular SEB236 power brush, just send me an email, I'd be happy to walk you through cleaning the brush on this one also. If you have any questions about this repair, please feel free to email with any questions, I really enjoy sharing my knowledge, and passion fixing vacuum cleaners.