Power steering question.
 

Hi everyone, Not sure if I posted in the wrong area beforehand, all I seen on there were threads with parts for sale so if so then I do apologize!

I just traded my truck for a 2004 audi s4. It is fairly clean and has 115k miles on the clock.

The guy I got it from claimed he had put in a new power steering pump, a new rack, and a new power steering pump gear sleeve. Now I went to drive it and when I test drove it the other night, it seemed to steer fine. Now when I got it home it feels like literally there is no power steering whatsoever. It is also making a chattering noise, I'm not sure if its related to that or another issue all together but it is fairly loud.

What could the issues be and how do I go about fixing them?