C5 primary bonnet latch issue

[fotobright]

Hi,

The primary bonnet latch on my C5 doesn't appear to be working. The secondary latch is fine. When i'm pressing the bonnet home so that it engages with the primary latch its just not holding and only engages with the secondary latch. The bonnet's not been opened for three months or so I guess. The cable release has a little play in it and a quick play with the catch mechanism suggest's it got some lubricant on it so not totally dry.

What should I look at first to resolve this?

Thanks

[GiveMeABreak]

Not sure - here's the parts diagram and the actual locking mechanism seems to be a single unit (No. 5).