Need to tighten the valve to the bezel. Looks like it would take some sort of specialized tool to grip the two parts. Do you know who made the valve? If so, do a search for tools for that valve style.
The same tool used to remove it should be able to help tighten it. Best way to tighten is with the tube fully inflated. Might want to loosen a bit first to make sure none of the cap string is stuck between the face of the cable and the tube creating your leak.
Best of luck,
Chris