My DC28 has great suction at the top but nothing at the roller? I have cleaned both filters & searched for the problem but can find nothing! Any ideas?

Try removing the soleplate from bottom of machine (rotate the 3 plastic screws to unlock position). Lift the soleplate off and remove any obstructions, dirt or hair that may be built up over the brush roller.

Check short clear hose for blockages or damage - if it is damaged purchase new hose.

Check the belts and the rotate brush roller, it should turn relatively easy. if it's difficult to turn by hand, remove the brush roller and pull off the end caps. The axle will come out with one of the caps. Now check the roller bearings and clean away any build up, replace end caps. If it's still stiff to rotate, you will need new roller.

Remove the two inspection ports and check them for obstructions, particularly common around the U shaped port at bottom rear of machine. this Then you can check the long flexi hose & metal wand for any obstructions.

If in doubt, call Dyson - They will help you troubleshoot. Let us know how it goes.