Power Steering and parts.

[97LSi004]

Two questions:

My power steering is still messed up. I watched the pump as a helper sat in the car and turned the wheel. The belt looked to be slipping. Maybe the pump is giving a ton of resistance, so it slips. The steering wheel shakes a little when this happens. If i put the car in drive and roll it about two inches the steering is noticably better, not perfect but moving it helps, driving is fine, only a problem when stopped or really slow. Why is this happenning??
Maybe i only need a new belt.
Which brings me to my next question: is there a good supplier online for parts? i looked at subaruparts and 1stsubaruparts, and i can't seem to find a p-s pump belt. I did a search for "belt" on both, and came up with only the timing belt.
-Ryan