Oreck belts keep coming off

Question

Hello,

I have an oreck XL upright and the belts keep coming off. I have cleaned it througly inside & made sure the brushroller was cleaned well. I did notice on the side of the brushroller where the belt goes on to is a little worn could this be the problem? Please help I cant keep going through belts every 5 minutes ( and I mean that literally) it's becoming very costly. Do you think a new roller brush would help?