Cable gland problem

I installed a cable gland in the place of the sharkfin antenna.
I have already sealed it with silicone.
My problem is that I neglected to fully tighten one of the cable gland nuts before attaching it.
I realize that I can plug the existing hole, but what happens when I want to feed another wire through? Even if there is some sort of way to get something that locks the gland shut from the outside (some sort of outside locking nut?), I’d have a loose locknut in the gland.
Ideas?

 

UGH! Remove JB and tighten gland. Clean up white silicone, use black RTV and wet finger to smooth joint. That looks terrible!

 

Not what I asked

 

Assuming the locknut inside is loose? Take the outer nut/seal off, and pull on the exposed threads as you turn it to the right to tighten. That “might” work if the locknut can get a bite.