This one is similar to Champion of Challenges and again doesn’t require too much skill. First of all select a song you wish to play (I suggest “2112 pt.5 – Oracle: The Dream” by Rush as it is the shortest on disc song (and it is fairly easy) and when it brings up the options for the song on the right select Star Challenges. This brings up the challenge menu for that song, scroll down to a challenge for your instrument (make sure to select high score) and select it. It will then take you to the little leader board in the middle, if you have already played the song highlight yourself and select. Now all you have to do is beat that grade (not score, so if the current grade is gold you need to get platinum or diamond), this shouldn’t be hard if you previously had a very bad run on the song. Once you have beaten your previously set grade the achievement is yours.