A few years back, a desperate and young family member called me to help with their power steering. It was an Oldsmobile with the same kind of pump. After one new pump, there was no power steering. (It was just very weak before). He had already changed out the pump on his own before I got there. I figured he just didn't bleed it properly, but after several attempts, we finally wound up in the wrecking yard and got another gear box and installed it. It worked fine. After questioning him at considerable length, guess what? He had stuffed the hoses with paper towels while he was changing out the pump. We bled the hoses into a coffee can before bleeding the whole system. Best I can figure is that some of the towel pieces got in the gear box and stopped it up completely.