DJ1000 channel 2 volume fader 'jitter'

Hi, I seem to have an issue with the channel 2 fader on my DDJ 1000. 

Without touching the fader, the volume seems to jitter up and down randomly. Video of the problem and some of my settings here:

https://www.youtube.com/watch?v=kcxgiW_lnn4

This makes it impossible to cleanly fade out or hold a volume level at the moment. It only seems to happen on Channel2.

Running windows, latest rekordbox and 1.12 firmware.

Many thanks,

Dave