[old_tv_nut]

When I got a chance to visit the WGN-TV remote truck at the baseball park in Chicago years ago, they had helical tape machines with dynamic head tracking that could do clear stop frames, or slow-motion step-by-step by simply rotating the takeup reel by hand - the servos would follow the manual reeling. They had glued a rubber cup-shaped door stop bumper on the face of the reel, so the tape operator could just stick his finger in and get slow replay at any rate the director called for.