Yes, they can wear out. Mine used to work, and then it didn't. There was a separate valve at the meter, but's it's in one of those "in the ground" things out by the street. So, IF
you've already got the tools and some experience it can be replaced as a DIY. The tools I needed were:
- Propane torch
- At least two pipe wrenches
- Solder and flux
- wire brush and sandpaper
I went to the hardware store and pieced together the parts which included a couple of unions (I needed to be able to slide the valve assembly in and out of a straight line of pipe), a stick of copper pipe, plus fittings to connect to the valve. I've done some welding and sweated copper pipes before, but it's been a while and I screwed up one of the unions by using some old flux and then couldn't get it clean enough.
Take the time to plan it out first, measure, cut and dry fit everything
prior to using any heat and it can be done. I don't have the complete parts list or priced, but I remember just the parts being surprisingly expensive (maybe around $100?), so don't be surprised if a plumber gives you a quote for a couple of hundred dollars.
Hope this helps! Let us know how it goes.