I have the same problem. It feels like I have no power steering at all in very low speed. I have changed the fluid, which looked fresh to begin with... turned wheel both ways to the max and held it to get the air out. ....Nothing changed.
I'm going to try to change the valve, hope on a cheap fix before going for the rack. ..... If I only knew what I was doing. Has anyone actually done the servotronic valve replacement? Is this a pain in the back or what?...You know because the whole rack is like $700