While I have never worked on a Dyson, in every other brand, a non turning brush is almost always a broken drive belt. Unplug the vac, turn it over, look for a plate where the air is sucked in and the brush is located. There should be 2-4 screws. Remove the screws and the plate and you should see the roller brush and most likely a broken belt. Go to a vac store with the model# and get 2 belts. You have to slide the roller out, put the belt on. The roller is usually set in a groove to keep the bearing plate from turning. Push the roller back in and put the plate back. Hope this works.