Can a 1990 Buick Lesabre be driven after ball bearings go on power steering pump?

the bearings are gone? more likely the veins are collappsed in the pump..if its not assisting and you still retain fluid then the anser is yes. inside those old pumps on the pressure side is a cartridge like insert called the filter assembly. its inside the pump and its purpose is to pick up any metal that would flow through the sysatem...sometimes this is clogged due to wear on steering box. at the cost of a new pump id replace it with rebldt rather than a do it yourself fix