Quick Question About Power Steering Pump

Been having a problem with belts walking off the pulleys and getting shredded and today I noticed that if I grab my power steering pulley I can pull it in and out about 1/8". It actually moves the shaft that pulley mounts to. What does this mean and would it cause my belt to walk off the pulleys?

Thanks
Dave
 
The PS pump pulley is pressed on. Remove the serp. belt, and rent a PS puller/installer from autozone. Check to see if the PS pulley is just loose and needs to be pressed in more.

If not, you need a new PS pump or new pulley, whichever is stripped.
Scott