97 Power Steering Pump Failure?

[cesna12]

I am new to these forums so forgive me if I was not able to find the answer from searches. This one seems different from the other problems I have seen. It is a 97 LS400. The power steering has been great until Wed night. It was 10 degrees F. When it failed. I heard some faint noise that got much worse very fast while it was warming up and noticed the power steering was no longer working. The pomp is very loud. I checked the level it is OK. There seems to be no circulation of the fluid in the reservoir. I have pulled the filter on the rack and cleaned it (it was very dirty). I have put the car in a warm garage to let it warm up. I have only owned this car for 6mos. The last owner told me he had replaced the pump not too long before I bought the car. The pump looks almost new. I suspect he cheeped out and did not buy a OE pump. Any input before I spend 500 on a new pump would be much appreciated. I am a professional mechanic with 15years experience in foreign cars and have never seen a pump fail like this.