Is that a ground wire or something? Or my eyes deceiving me?? My brother-in-law has one he hasn't put up yet. I don't remember seeing that on his antenna, but then again I didn't really look at it like that. Check that you're coax is good by placing a dummy load at the end and putting some power to it. The VSWR should be good. 1:1 or very near it. And impedance as well. If you use an antenna analyzer, make sure R=50 or at least within spec of 50ohm coax. X should equal zero or agin, very close to it, and VSWR should be 1.0 or very close to that. As long as you know the dummy load is good and that your VSWR meter can take a bit of power, if possible put a bit of a carrier on AM. Like more than a few watts. 10 or more watts. Just to make sure the coax isn't hiding something. A sliver of wire arcing over when power is applied.
There also Might be a way to check that antenna as well. I don't know how it's put together, but you should be able to check part of it. Or am I way off base. Like I said I am not familiar with the antenna. I do know to keep the weather proof under that lip though and not to go around the actual mounting post as well. This will create issues as there is a drop hole like M0GVZ stated. Not saying you did, just bringing it up is all. Heat shrink makes for good weather proofing. The good stuff with the glue in it and heat it slowly and mushroom it out as you push it up to get it seal to the bottom of the antenna. Then start your electrical tape. If possible use 2" then 1/2" 3m tape. Again, not that you don't know all this, but it never hurts to jar the memory!! I hope you find the issue or if not, that Solarcon at least makes it right!!!