Currently Being ModeratedJan 3, 2013 7:39 AM (in response to iKusko)
The additional loops should be shown at the AppStore as update.
If GarageBand came preinstalled at your mac, did you already accept it at the Appstore to your AppleID? Otherwise you will not be able to update using the AppStore.
- Double-click the App Store icon in the dock.
- Enter your Apple ID and password.
- Click Purchases.
- If you haven't previously accepted your bundled iLife applications within the Mac App Store, you should see your iLife applications appear in the Accept portion of the screen. Click Accept.
- You may be asked for your Apple ID and password once again. Your iLife applications now move to the Purchased section. These applications are part of the software that came with your Lion based computer. Your account will not be charged for them. Click Install to complete installation of your applications.
But that alone may not suffice.
To make the additional content appear you may have to do the full monty and deinstall GarageBand completely, reboot, then reinstall.
When selecting a loop to update, selct to "Update later", and then open the App Store to look for an update.
See Dagon's post here: