Please Help! Dyson making horrible grinding noise after hoovering rug?

Hi, I used my DC04 Absolute + to hoover a rug with tassles. I think a tassle got caught temporarily & since then whenever I put the brush to the down position the hoover is fine for a minute or two, but then it makes this really loud horrible grinding noise as if the brush is catching on something.
We have taken the brush out and all seems fine. Unable to get to the switch where the brush head release is. Any ideas anyone?