To initiate a turn the steering seems "locked" and I have to jerk on the wheel to get it to turn. Especially difficult turning left, and not so bad turning right. The farther the steering wheel is turned, the steering gets much easier so as the turn approaches the stops either way, the steering feels normal. Opinions requested as to what may be wrong. I haven't ever been into this type of steering gear. I have considered three things: worn teeth on the sectors, worn out ball nut assembly, and worn or damaged steering shaft bearings. Please tell me your experience with steering problems you've had. Thanks