The spindle that the spare wheel goes round?

[tomjj]

Hi,
In the boot of the Mk5 where the spare wheel goes it goes around that plastic bit that you screw it down on to.

On top of that little plastic thread bit is a little push top. I noticed mine was broken.

Sorry if this does not describe it very well but does anyone know what that little push top is?

Thanks.

EDIT: Found a picture. The black plastic bit in the middle of the picture is what you screw round to secure the wheel. It has a black plastic lid thing that clips in is the bit i'm referring to:

http://lh5.google.com/kozlov.m.a/RuHpnNDr4hI/AAAAAAAAA5M/drpK7BIm4SQ/s640/DSC04613.JPG