After about 4 months of fantastically reliable use, a rear wheel fell off my Granite. It appears that the wheel hub spline simply pushes into the drive shaft receptor. I don't see any grub screws connecting the parts. After pushing it back together it keeps falling apart. I have tried glue without success. Am I missing something here? Is a new drive shaft the only solution? If so, will it need to be glued to the hub spline?