I always replace non-frostproof hose faucets since it is not worth my time or your money to repair them. The one problem you could have as a DIY’er is if the old valves are sweated to the pipe from the wall. Then you should install an adapter so the new valve can be screwed on to make future replacement easier. And to make your installation safe and legal, always install a hose vacuum breaker on the new valve. Secure it by tightening the set screw until it breaks off.