When they get like this (see below) you really need to pull it apart!
I should have taken more photos but my hands were to grubby.
Bottom up remove all the screws and split the unit.
Pull out the roller brush and remove the plastic end bearings.
Clean the brush itself and also clean the end of each spindle.
It’s likely you will need a sharp knife of scalpel to cut off the crap.
With a pair of tweezers clean out the inside of the plastic bearings.
If the poor thing has been really abused the heat generated from friction may have damaged the bearings.
Check the toothed belt for damage and stretching, if needed get a new one.
Remove the clamp screws that secure the long impeller bush.
Remove the circlip and slid the bush off the impeller spindle.
Clean everything and lightly oil, slide the bush on replace circlip and put aside.
Clean all the crap out of both shells, use tweezers to pick out the stuff.
Position the impeller assembly and secure with clamps and screws.
Slide the bushes onto the brush, pre-align and hold with left hand.
Right hand picks up the belt, first over impeller and then the brush drive wheel.
Tension a bit the align and slide brush into end mountings.
Put on top cover and wiggle fiddle to sit it down, work around edges to bed down.
Holding everything together turn the thing over, drop in and screws and tighten – done.
