i just bought my first glass call a custom power crystal from primos. the little conditioner stick they give me just didn' t cut it so i started useing some 100 grain medium sand paper but how do i know when enough is enough. it is making good noise but it seems like sometimes the stick kind of slides on the glass and goes silent. i feel like i have done it enough and dont want to do it too much but how do i know when i get to that point??