Sounds like you need to find a competent gunsmith down there in the NO area. I've had a number of Security Sixes in the past and still have a couple, one from my Dad, and none have or had what your describing..Get it fixed and you'll love that revolver.
Thanks, wasnt sure after googling it people said it was normal, was woried because it wasnt shoot since 1980 ish and the rattle started. Some say it needs to rattle.