Power Steering Issue

Increase engine speed. If power assist returns, the vanes are worn in the pump. If that doesn't help, pull forward on the pulley, (engine stopped). If it moves forward, the shaft is broken.

If neither of those things is the problem, you'll need an inline pressure tester to determine if the pump is not supplying pressure or if there is internal leakage in the rack and pinion assembly.

Power steering pump. I had one with a broken shaft. It sealed just fine and there was no wobble or anything to indicate it was broken until the belt was removed. That's when I noticed the pulley would spin very easily by hand, and it could be pulled away from the pump. You probably won't be able to identify that unless the belt tension is removed.