Rebuilding a power steering pump. How difficult?

Agreed, if it's just a leaker and otherwise works ok, not a big deal. The hardest part is the pulley seal. You just need the correct puller for the pulley and a way of pressing it back on. do it with the reservoir off so you don't damage the reservoir or it's "O" ring. I use a cheap dent puller slide hammer with a screw attachment to remove the seal.