You can probably get the screw from gunpartscorp.com or jackfirstgun.com. A hammer is going to have to come from someone who has old gun parts. Numrich doesn't list the .38 SA in their inventory.
DWalt,
The "safety-cock" notch is gone and the full-cock is not anywhere near where it should be. Evidently someone did some home modifying on it at some point. Lock up is tight, bore is good so I didn't want to junk it!