Reply to Best Settings For Tight Scratching?

I've not had any luck finding the right Sensitivity , Acceleration and hardware settings to get the VCi-400 Scratching with Traktor. I find that the cue point keeps "slipping" making scratching impossible. Have any of you guys managed to get the VCi-400 Scratching properly? What settings did you use?

ps. Scratching response is perfect in Serato DJ Intro so the hardware is all fine...