@Malcolm Wilkes  I’ve heard of a similar issue where a part called the Vball starts to wear (you can view that part here, for reference : https://www.dyson.com/support/journey/spare-details.966817-01)

Still, that’s on hard floors, not carpets.

I would indeed inspect the brush bar - go ahead and fully remove to from the head by using a coin to open the end cap  - then check those bristles, etc. They can wear and the brush bar can be replaced.

The V8 is brand new. So it’s not worn out! 

@Malcolm WilkesAre you referring to a line on the carpet where it’s visible that the carpet was vacuumed?

If so, that’s normal for any vacuum with high rate suction running over carpet with a heavy underlay or thicker pile. This is caused by the dense material reducing the airflow and pulling the cleaner head closer to the floor.

Feel free to post a image here and perhaps other members of the community can chime in with their thoughts.

If you wanted to discuss it further or speak to Dyson regarding the next steps, please use our ‘Contact Us’ option on our Visit Dyson.com link. 

Adam.

It’s not normal as it hasn’t done it before and if it was supposed to do it Dyson should tell you. Definitely don’t want tram lines all over carpet!! 
tried 4 times to phone Dyson and each time they have hung up mid conversation they don’t even phone back even though they have your number. Customer services or rubbish!