Washing Machine Outlet Box

I think I have to replace a couple of those old screw down valves. I had a plumber come out and he put on a couple of brass hose bib ball valves, but the hot water one weeps around the ball. How do I get the outlet box off or install a new one to sweat a joint? Do I have to dig into the drywall?

box

There are only a couple of brands of washer boxes that use a valve that screws into an adapter in the box. For all the rest you have to open the wall and change the connection under the box.

The plumber heated the valve to much. Call him back and have him replace it.