Hi @Emma.S 

I have an old dc18. The first ever with the Dyson ball. Never had a clicking problem. 

Super interested in all thinks Dyson, so I Googling this. I discovered an older post an a forum named Fixya - https://www.fixya.com/support/t24817528-clicking_noise

Clicking is caused by the filter needing to be repositioned and rewashed. They’ve shared a handy video which could help.  
 

Good luck 

kirby

My Wife had a dc24 when we first met. Great little machine. 

We found if the filter dried on the radiator instead of naturally that it would warp somewhat. Meaning we’d need to wash it once again and hope it went back into shape. We ended up getting a few from dyson FOC.

If washing it again doesn't fix it, I'd suggest giving them a ring and getting a replacement. It being a second hand dc25, you’ll probably have to pay for it. 

I’d be interested to hear how you get on. 

David.

Hi

Thanks for the help

It was still happening after the recommended rewash. I call Dyson and a lovely South African lady arranged for a new filter to be sent in the post.

Apparently it common on the older machines. Something to do with a warping of the plastic.