I have a leaking water shutoff valve (pictured below). It appears to be a sweat shutoff valve that is soldered on to the pipe. It does not leak if I tightly shut off the valve, but any attempt to open the value causes leaking (admittedly I have to close it pretty tight to stop the leak).
Obviously I'd like to fix this through the easiest method possible. I could replace the entire valve, which would require either cutting the pipe or removing the soldering and pulling the valve off. However, there are valve stem repair kits that would involve just replacing the valve itself.
My main question is, is this a viable way to repair the leak? Given the fact that it doesn't leak when fully closed, does that imply a failure of a o-ring that such a repair kit would replace? Almost all advice I can find about replacing water shutoff vales involves replacing the entire valve, not just the stem.