I have a DC01 vacuum and changed the motor recently. Since then there has been large clumps of dirt and dog hair building up in the pre motor filter compartment (accumulating on the side of the filter that's closest to the outside of the Dyson).
I dissembled it, thinking that a seal hadn't been made somewhere when I put it back together, only to find that the motor compartment was also full of fluff and dog hair. I cleaned it out, ran the motor without reassembling and everything seemed fine. As soon as I put it back together and ran it for a few seconds however (without actually vacuuming the floor) the dog hair and dirt built up behind the filter cage again instantly. I have no clue where it might be coming from other than if it's being sucked back out of the bin.
Does anyone have any ideas about what could cause this?