I had an 8 inch smooth wheel I think it was 60 Durometer . It worked good when it came time to repoace it I bought a 6 inch smooth wheel that was supposed to be like a 100 durometer .Now I'm not getting a smooth finish it leaves lines across the blade . I'm not sure if it's the diameter of the wheel or the hardness of the wheel .It's seems like most people are not using a smooth wheel. Does anyone have any suggestions