I remember when I used to play parts roulette also. I did it with the power steering on my previous turbo supra. The pump had a whine and the steering was no longer assisted. I replaced the pump twice and and the rack once. It turned out to be the fluid reservoir had clogged and starved the pump, then damaged it.
After reading this thread, I've come to the conclusion that it's a fairly common problem, and I suggest you do the same.
Edit: I just realized that you might think I meant to go replace the res and see if it'll solve you're problem. I meant CHECK to see if it's clogged and replace IF necessary, 'cause that's how you diagnose a problem.
I've also just realized that there's a good chance you went ahead and bought the manual rack huh.