I was having a friend help load one of my rb67 backs and somehow he managed to wind the entire roll of film over to the take up spool. the back was definitely closed so i dont know how this happened. In any case, now the film is at the "exposed" stage without ever having seen any light. does anyone know if it is possible to move the roll back over to the left side and shoot it starting from the "exposed" end? Or is there any other way to salvage the roll?