I suspect your sector is worn out in the straight ahead position. One of mine was this way. I could adjust it out but it never seemed to feel just right. Once I replaced it with a NOS piece of e-bay, it drove just the way I thought it should have. The old one had depressions were it always rode the most.
Glad you figured it out, when they are right, it sure is a good feeling knowing its going to go where you point it.
Joe
