DC25
My wife got some table cloth jammed in the brush bar.
When pulled out suction ok but no brush bar rotation.
No hair or thread on bar to impede rotation
Followed these intructions see URL below, to remove brush bar.
Brush bar drive shaft seemed a little stiff and after a few rotations by hand seemed better.
Replaced brush bar and immediately worked.
Not sure what the diagnosis was ? drive shaft jammed ? some kind of protective jam.
Worth trying this simple routine before trying more complicated dismantle !!
https://www.youtube.com/watch?v=6Yc7h4WgDNw