Loud clicking noise when vacuuming (not in the upright position)

"In addition to the clean-up of the hair, string, threads, wires, and who-knows-what that gets routinely tangled around the brush bar, every now and then a more intensive clean-up is needed. This is not in the manual, but eventually the debris can tangle around the spacer in the brush roller end cap creating enough friction to melt the roller and make it stick.

I made a guide for how to clean that out here: Dyson DC33 Brush Deep Clean"

"You've probably got something jamming the brushbar.

Unplug the vacuum and tip it on it's side and have a look at the brushbar, you may be able to see what's stuck and remove it.

More than likely the brushbar will be clogged with hair and this is jamming it up, I use a craft knife to cut through all the hair on ours to free it all off."