I haven't listened to the William Tell Overture in years but there isn't any quarter notes in that song is their? I remember that song as being very fast. If you're working on that song not sure why you are having problems with your timing. Fast songs like that you can't really tap your foot or anything, you just really need to spend the time to learn it so you hear it in your head while you play if that helps. I can't tap my foot and play at the same time. When you play slower songs you can try tapping your heal instead of your toes, seems to work better for me Good luck and would love to hear you play that song, it's fast....