[Supras] Power Steering Problem?

[JAMES]

Hey,
        I have been having to add power steering fluid pretty often. So to delay fixing
        it, I put some "Lucas Power Steering Stop Leak" in it. It did slow the leak.
        About a week later the power steering pump started to make a small whining noise.
        Then one morning when it was very cold (about 20 degrees) I started it up and as I was 
        backing up, I noticed that the steering was so stiff that I could  barely turn it.
        I turned the car off and was going to check the fluid. The fluid was coming out from under
        the reservoir. When I took the lid off it released pressure.
         The next day when it was warmer I check the fluid and started it again. This time
        the fluid did not come out but the steering was stiff. I drove it to a shop and the guy
        replaced the pump with a low milage used one. 
         Now the steering is still a little stiff and you can hear a little whine when you are
         trying to turn the wheel.
          He said that the "rack" is probably bad. He said that some times when the pump
          goes bad that it will stop up the rack.
            I have heard on this message board before that sometimes you need to clean the screen
           in the reservoir. I also wonder could the stop leak might have stopped up something.
           Are they anything that I could flush out the system with? Any suggestions would be appreciated.
                                                           Thanks,
                                                                         James
                                                                          89 Turbo