Power Steering Main O-Ring
 

Asked before but did not get any satisfactory answer. I need to change said o ring but do not want to remove pump from car. It seems to be a simple matter of removing the cover, replacing o ring, replacing cover and topping up fluid. Are there any components, springs or tiny steel balls, that might go flying when the cover is removed? Or might make cover replacement difficult? Anyone with experience on this?

Not sure "which" main o-ring you are talking about? In the "common diy threads" post at the top of this section there is a link to online manuals-once you download it-start at sect 17, page 36 for a how to.

I just think those PS hoses seal in there with the o-ring. I don't think there are check valves.

Make sure you have something underneath to catch any fluid that leaks out. I think PS fluid can damage paint like brake fluid.