It's not a recirculating ball box, it's a simplier 'worm & roller' box, so pull one a part, clean it up & you should be able to get the seals from a regular bearing shop. They usually need a couple of shims removed from the bearings that hold the input worm before adjusting the sector + only adjust the sector screw with the box centered. Worm & Roller steering boxes have a lot of 'natural' play in them when turned away from centre, but caster keeps you from noticing it. As others have said, you may need to move the pitman arm around by one spline particularily with non-genuine tierods or racey wheel alignments.