Lurching when engaging clutch

Hi All,

I had my primary clutch replace about 6 months and 400 miles ago and it is working great. Problem now is when you ease on the throttle the clutch starts to engage the vehicle jumps and lurches until it starts moving and there is a vibration in it. I think there is a bad spot in the belt. Anyone with advice on what belt to buy and procedure to replace??

Thanks
Stosh