For panel holes that are worn such that the standard SK-R4G Retainer will no longer retain the grommet/stud, there are three options in order of preference: 

1)      Use SK-R4T Retainer with a wider diameter.  Advantage:  Expanding the hole for the SK-R4T is not required.  Disadvantage:  In some applications (thick panel with a standard grip grommet like the G, H, N, or O grommet), the SK-R4T may not fit.  Plus, once it is on, getting it off is a real chore. 

2)      Use SK-R560 Backing Retainer and reinstall SK-R4G.  Having these parts as spares can quickly resolve many maintenance problems with fastener assemblies (the grommet and stud) that fall out of the panel when unlocked.  Advantage:  Allows full grip range of existing grommet and allows use of the standard SK-R4G Retainer.  Disadvantage:  The worn hole must be .531 or reamed to this diameter for the SK-R560 to properly slide onto the grommet. 

3)      Fill the hole (fiberglass panels) and re-drill proper sized hole (15/32 to ½ inch for thick panels).  Disadvantages are obvious.