Antenna Mast

[Monamee]

I want to put a car cover on the 2005 C5 hatchback. The roof antenna mast looks like it should unscrew from the base plate however, there is a lot resistance when I attempt to twist the mast. Is it supposed to unscrew?
Regards

 

[dimistyle]

Yes mast unscrews from base.

 

[Monamee]

Thank You

 

[Monamee]

I tried unscrewing it but it feels like the internals have rotated inside base and now the seal has been disrupted. l think the whole unit will now have to come off. To do that it looks like the roof lining head board will have to removed.