Loosen the lock bolts. Tap on the bolts to loosen the lock plate in its mortise, and then finish unscrewing the lock bolts from the stock. Remember to put the hammer on half-cock. Once the bolts are removed, the plate should fall into your hand, or lap.
Use an old toothbrush with soap and water to clean everything that doesn't look like bright steel out of the lock. Then rinse and dry the lock, and then oil it. Check all the screws to make sure they are screwed in properly, but don't try to screw them in too hard. Treat this lock and its parts as if you are working on a fine swiss watch!
Once the parts are oiled, you can reassemble the lock in the stock. Check the lock mortise to see if there are chips of wood in there. Take them out. Then also note if there is any kind of stock finish in the mortise. If not, put some in there to help seal the wood. That keeps oil and water from soaking the inside of the stock, at its weakest point.
If you have any experience with Epoxy bedding compounds, mix up some, put release agents on all exposed metal parts, and use a q-tip or some small paint brush to lightly spread epoxy over the surfaces of the lock mortise. When it hardens, it will strengthen the stock, as well as seal the wood from oil and water.
