It is my STRONG opinion, and Art's as well according to his video, that you CAN NOT "Fix" a Salt stock. It must be destroyed, no matter how purdy it is. You just cannot extract the salt from the wood. Now, that said, you CAN fix the metal. Just watch Art's video. Enough time and money spent will repair any salt damage to the metal, but not the wood.
This doesn't mean salt guns are useless. There are several people who look for high grade salt guns at bargain prices, and install all new wood and fix any metal corrsion.