AC Valve Leak - Any Experts?

I have a 2001 Venture (50,500 miles) that has a leaking AC Valve. I believe it is the "low side service port", but I am not sure. I have included a picture of it below.

Here is the issue: My mechanic found this problem and REPLACED the "core" already, but it still leaks! He believes that at some point in time the core that was in there was over-tightened and somehow damaged the point where the core seals (the base appears to be aluminum).

At this point, my mechanic (not an AC specialist) wants to know what the next step would be. He doesn't want to replace the entire AC hose (I think it is the "suction hose") as it would cost $200+ just for the parts.

Any ideas?

http://www.links-to-golf.com/images/ac-service-port.jpg

Thanks,

Find a metal cap that can be screwed on like a tire valve cap would. I would also put a little bit of sealing compount on the threads and then screw the metal cap tight. This should stop the freon from leaking past the bad valve in the body of the hose.