While filming the movie "They Came to Cordura" (1959) with Gary Cooper and Rita Hayworth, he suffered a permanent, disabling back injury. In York's own words, "Gary Cooper and I were propelling a handcar carrying several 'wounded' men down railroad track. I was on the bottom stroke of this sort of teeter-totter mechanism that made the handcar run. I was just lifting the handle up as the director yelled 'cut!' and one of the 'wounded' cast members reached up and grabbed the handle. Now, instead of lifting the expected weight, I was suddenly, jarringly, lifting his entire weight off the flatbed-180 pounds or so. The muscles along the right side of my back tore. They just snapped and let loose. And that was the start of it all: the pain, the painkillers, the addiction, the lost career."