Try this. It worked for me. My icon is now green and it looks like I have the same imac as you do. Pam
In the Finder:
> Select the orange TM icon, and then press command-i to display the drive's Get Info window.
> Select "Go" from the Menu Bar
> Choose "Go to Folder..."
> Enter: /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources
        Press "Go"
A new FInder window will appear. In that new window:
> Search for "GenericTimeMachineDiskIcon.icns"
> Press Option, and drag the file's little green icon onto the small icon at the top left of the TM's drive's "Get Info" window.
The tip is the comment by David Brick in reply to this article's suggestion which doesn't work.
http://www.macworld.com/article/3033807/...on-changes.html
