Replacement spare part for channel fader 1 on DJM900Nexus and DJM900SRT. By replacing this part you will most likely get rid of bad connections on the channel slider. You may also have to clean the fader mechanism on your DJ mixer to get a smooth fader going again.
If you are good ad soldering and have the time it may be worth it to just replace the fader component itself: DCV1027. This fader is used on all 4 channel faders on various DJM mixers from Pioneer DJ.