I've got a 85 351 power steering and well my steering is loose there's play when I turn the wheel the steering shaft will turn but the wheels won't they will to some point but not at first

Here is a link to a video on YouTube showing the problem

http://m.youtube.com/index?desktop_u...?v=Ap8kd9E_444

If the link doesn't work here on YouTube search jbexoticsinc the video will be on there thanks in advance for the help