I don't have any suggestions, but a couple of comments.

1. Manual steering boxes are quite easy to work on. The biggest deal is don't lose any of the internal parts. For example, in a recirculating ball design don't lose one of the balls.
2. It sounds to me like your box has adequate lubrication. There is or used to be a Mopar-specific steering box lubricant. When I did my own box I used NLGI #1 moly grease because that was what I could find at Walmart. I let the grease sit in the sun so it got quite runny before pouring it in. The Mopar guru E-booger has suggested a 50/50 mix of, IIRC, NLGI #2 grease and 90wt gear oil.

Good Luck!
R.