![Headbang :headbang:](./images/smilies/headbanger.gif)
Dirt can build up under the blue twist knob and jam it which stops it clamping in the socket so I took the knob off and found the red and green plastic inserts had broken and were stopping it working so I took them out and now it works fine
![Thumbs Up :thumbsup:](./images/smilies/smilie_thumbsup.gif)
So if anyone has the same problem there is a simple fix. The only problem is without the red and green inserts, theres no indicator showing it's in the fixed position but you know when it's fixed as it makes a loud clunky noise, I'll speak to witter and replace the plastic inserts when I get back.