Managed to fix the aerial, it had simply become stuck. It's clearly been replaced already with an aftermarket generic item. Fairly easy to get to once the trim was taken off along the rear of the boot and around the carpet to the left of the boot. The CD multi changer whips out with 4 bolts then there's easy access to the aerial.
Where the aerial retracts into the tube it passes through a nut which secures it to the car body, this was caked in a white chalky powder, a quick whizz with the dremmel type tool and all clear again.
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The Garage
Audi A8 D2 PF - 1999 - 4.2 Quattro Sport in Silver - Bose, Blinds, S8 exhaust, FL armrests, S8 Brembo's.
VW Tiguan 2.0 TDi Bluemotion 2013 - The OH's company car & general family runabout.
Honda Transalp 1999 XL600 VR - My runabout
Honda CX500 - The winter project 2014/15