Or …. my Dyson V6 vacuum starts, then stops.
If I remove the filter, it magically works.
So it’s a blocked filter, then.
While waiting for a new filter from Dyson, I watched this video from Stampy on cleaning and servicing the Dyson V6.
While the pre-filter LOOKS sealed, you can take it apart. In the video, Stampy quickly shows this, and it wasn’t clear from the video how it fitted together.
After a bit of puzzlement and the use of an iSesamo pry tool, here is the filter separated.