My mom had neck surgery just this November and is extremely, extremely weak in her left arm due to a compression of the spinal cord - meaning no matter how much she might exersizes her arm she would never regain strength. That said, I thought she was basically screwed in terms of racking the slide and so instead taught her to count the shots so that one bullet always remained in the chamber and racking it for her.
BUT that link fixed it all. The information in that link taught her to rack the slide effectively and easily, and thats with the 709.
Try it. Let me know how it goes.