How big's my aerial nipple?

I thought that title would get your attention!

Basically, I've been fitting a Parrot system which works wonders, but now I've refitted my radio, the reception is virtually non-existent. I've tried with an old Sony headunit too and it's the same with that.

I have a feeling that I may have snapped the central 'male' core of the aerial wire off, even though it looks normal. There is only about 1-2mm of nipple left, should it be longer than this? If so, if I were to fit crimp a small diameter copper wire in, would that do the same job as the original core I.e transmit the signal into the radio?