WingShot 2 reseal

I just pulled out my wing shot, and discovered it is no longer holding air, leaking through the barrel. I've tried firing it, filling it slow, and blasting it full to try and seal the valve to no avail.

Is there anyone out there tuning korean guns that could reseal it? It was power tuned by will piatt, not sure the exact details of those changes other than "power tune", and it puts out ~300fpe now. I assume that may make a difference in seals.