Strip it down and give it a good cleaning. The Russians used a thick oil to preserve the metal and wood. If not removed can cause issues that could be very bad (Deadly) I used kerosene and it worked great. Look in the red rifles forum, there are some stickies dedicated to the SKS. In one of them there is a link to a detailed strip of the SKS. Also strip the bolt down and clean it out. When you put it together you should be able to shake it, and hear the firing pin rattle around. After you strip it, soak the small bits in a cleaner, as I said, kerosene works great, and wipe the stock and the rest of the larger pieces.