I also own an SKS that was brough back from Vietnam. I bought the rifle from a GI sometime in the late 70's or early 80's at a gun show. He told me he had the Bring Back Papers, but I never received them. It is a Norinco SKS made in China in 1966.
I hope they give you a new rifle!
I had a problem with a Ruger. Ruger replaced the rifle no charge, no problem!
Rugar has always had great customer service!