Hotpoint Aquarius vdt20?

I recently replaced the belt and since then the drum seems to be rubbing on the back panel and making a scrapping noise that can get worse the longer it's on to a point where it becomes unbearable. We had the problem to a much lesser degree before the belt change so I wondered whether it is a common problem with this make appliance and I have done something to make things worse? Any help would be much appreciated.