Power Steering Noise

My 04 Western Star has over the last week or so started making a noise when I turn the wheel. Has the sound and feel of a pump thats starving for oil. Went and bought a new filter yesterday, put it in, topped up the oil (it's red, so I used ATF). Started it up and tested it but did not seem any different. Haven't driven it yet, will be doing a load this morning. I did observe the oil to be very foamy when I looked at the dipstick after my little test. Not supposed to foam, is it? Can there be something going awry with the pump? It's gear driven, no belts. Thinking to change and refresh the oil and see if that helps. Any other ideas? 1.04 million miles on the truck, most likely still the original pump. Thanks.

 

Problem fixed! Thanks Shooter! It was a fitting on the side of the pump, behind the frame. Kind of a big nut. Was actually finger loose, but didn't see a lot of leakage there. Was sucking air in tho. Boy if every problem could only be fixed this fast and this easy. And maybe,just maybe this will help somebody else with a growl in their steering. Thx again sir.