I just received a used steel Merckx frame through Ebay and I have notice there is rust in the frame. I have cleaned out the seat, down, top tube and chain stays but there is a rattle of debris coming from the seat stays. Unfortunately, there is no way to get into the seat stays (as far as I know.) And the rattle of the debris inside the stays is going to drive me nuts.
Any recommendations or magic tricks to fix this situation.