Unlockable: Guitars
The Log Guitar: Get 5 Stars every song on Expert Mode.
Axe Guitar: Complete Expert Mode.
Casket Guitar: Complete Medium Mode.
Eyeball Guitar: Get 5 Stars every song on Hard Mode.
Fish Guitar: Complete Easy Mode.
Snaketapus Guitar: Complete Hard Mode.
USA Guitar: Get 5 Stars every song on Easy Mode.
Viking Guitar: Get 5 Stars every song on Medium Mode.

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Bug - Hardware Glitch

It seems there is a slight problem with the whammy bar on the X-plorer guitar controller. The defect is related to how the whammy bar functions as it doesn't register an input downwards to start the whammy effect; instead you must pull the whammy bar up and then down for it to work.

This isn't intuitive and many are complaining that it takes an extra second away from performing the bending effect on long notes. Sometimes, it doesn't even work at all. My brother has played this game before on the Playstation 2, and he has confirmed that the whammy does not work properly on the Xbox 360 as it does on the PS2, where as that controller responds to any input you place on it regardless of direction.

Red Octane is recommending leaving the buttons alone (as well as the whammy bar) while powering up the Xbox 360, or plugging the controller into the console after the Xbox 360 is booted. While this might work for some, this looks more like a mechanical rather than digital input problem.

Although the game isn't totally dependent on the whammy bar (you could play without it) but it is an integral part of the game when trying to achieve Star power status from long notes (and lower your score).