The film stops abruptly while playing (Pictor)

The Pictor can sometimes struggle to keep a proper tension on the film when using very light reels as supply, e.g. the classic Kodak super 8 3m/50ft plastic reels such as this one:

The solution, and general advice, is to transfer the film to another, bigger, reel when preparing it before the scan. Several small reels can also be assembled on one bigger reel to avoid multiple handling and threading on the scanner.