Another GUI for WBFS (Wii Backup File System) version 2 is now available, which is the file system Waninkoko's USB Loader uses.
This one by Maximillion is a lot more stable than the previous GUI posted earlier.
If you're having problems with the previously posted one, then give this one a shot.
Download: Wii Backup File System (WBFS) GUI v2
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