Thanks for the ideas. What I found once I got in there was a pipe fitting screwed into the valve. When trying to unscrew the pipe fitting it appears that it is brass and either soldered to the brass valve or so corroded that it was tight enough to to strip the head of the fitting when trying to loosen with an open ended wrench. Now my problem is how do I get it out? Do I cut the copper pipe below the plug and do a splice? If so, how might I do this?