I have a vintage Faultless Miniature, one of those cheap bakelite cameras that has the cheap Graf lens. It takes 127 film, has a vertical frame instead of square so you get 16 images on a roll. With two red viewing windows on the back, do I advance the film so that I just move the frame numbers from the first to the second window or is there some other trick to it? I ought to know this but don't. I'm running a 13 year old expired roll of film through it so if I get it wrong its not a costly loss.