Stuck Polaroid roller.
Although I have a back for the Pro S, I have never used it yet. However, I have had several Polaroid cameras over the years and I have never seen a Polaroid where both rollers did not move. I think Polaroid always suggested cleaning the rollers with just plain water. All the rollers I have seen were made of stainless steel, so if yours is stuck due to developing gunk, I would just soak it in water for a few minutes and see if that helps to free it up. Other than that, it is stuck for a differenct reason that is causing it to bind . Hard to say. Ric.