Wondering if these sound like syptoms of a bad PS pump or the rack...any ideas?

GF's 96 2.4 Sedan feels 'notchy' when steering around a parking lot or that type of thing when the wheel takes more than 1/4 turn or so past center in either direction. Doesn't make any noise normally, but will squeal the drive belt sometimes when it's 'notchy'. I can see the belt slow/stop intermittently when it does this.

I've not had to troubleshoot a steering system before, so I'm asking you guys who perhaps have.

Thanks a ton for any input you may have.