Hi @eleanorennis
The [https://www.toolservicenet.com/i/BLACK_DECKER/GLOBALBOM/QU/BDH2000PL/1/Instruction_Manual/EN/90617822_BDH1600PL.pdf|user manual] doesn't show how to replace the brush, but looking at 1.11 minutes into this [https://www.youtube.com/watch?v=kqzcbZZWm5k|video] and the shape of the brush (search for [https://www.google.com/search?client=firefox-b-d&q=B%26D+90552386|B&D 90552386]) it seems to just clip in to the nozzle. (supplier examples only to show brush part)
Hopefully this is of some help.