Leaking TV aerial

We have been finding some water in the wardrobe now and again over the last 2 years, but never been able to see where it was coming from.    The suspects were the awning light fitting, which also doubles as a wardrobe light when you open the door, or the Status directional TV aerial mount.

Both have been checked twice at the annual services, as has the roof/wall joint, and no leaks found.  

Today, while removing some stuff to ready the van to be used by our daughter, we found wet  chair pads in the bottom of the wardrobe directly below the aerial position, so that must be where the water is getting in.

The seal on the roof is fine, so after some googling and u tube watching, I have concluded that it is the aerial itself that is leaking, either through or round the mast.

Has anyone had this problem and fixed it, or will we need to invest in a complete new aerial?