I would agree with the others who are suggesting Auto-RX, in the event that a seal issue could be worth a shot. You'd only need about 1.5 ounces for your system, so you could use the rest of the bottle to treat your transmission, differential, or engine.
If you notice a great improvement, then fully purge the system with Redline or Royal Purple power steering fluid.
If you notice a great improvement, then fully purge the system with Redline or Royal Purple power steering fluid.