B.A.P. sold me a 2WD steering gear box but they claimed it was a 4X4 box ~ sh_t liars, I was out $450.00..! I still have that damn thing & spent $100.00 expoxy painting it red before realizing it was the wrong box for my truck..! I disassembled it to see if a 4X4 sector shaft would fit BUT it will not ~ in the process, I noticed their rebuilt box sector shaft was full of wear marks at the seal area, crap rebuild..!

Hmmm, what was happening before that caused you to buy a rebuilt gearbox..? The same thing..? All I can think of would be the power steering pump is not putting out enough pressure..? Especially if all the lines are clear, no plugs...

Better answers will be coming your way I'm sure...
You can fix it, no worries, might take time but you will get it done