What would cause steering to become stiff at far left.

[vernonreeve]

I have a 1999 Malibu Response LX, and the steering wheel rotates freely throughout the entire range, except when I turn it all the way to the left while sitting still or idling.  It becomes stiff the last quarter of turn, and feels like something is sticking.  It vibrates a little as it feels like it is sticking and releasing then sticking again.  The rudder doesn't have any play in it so it seems fine.  It's fine when I turn it all the way to the right and back. Any ideas?

[notaloser]

Did you notice a gradual change or did it occur all of a sudden one day? You may have some debris or moisture that’s worked it’s way into your steering rack at one end. It’s also possible that the block where the end of your steering cable mounts in the engine compartment has worked its way loose.

Be careful! If the latter is true, it is possible to steer past an “inflection” point and you could get your rudder trapped in the rotated position and be unable to straighten up without manually repositioning the rudder arm in the engine compartment. If that happens while you’re under power and steering is critical, you will have a bad day. 

Make sure that block is tightened all the way down and that it doesn’t move when a friend rotates the wheel all the way to the sides.

[vernonreeve]

The block that the steering cable runs through feels tight, but I'll have someone watch while I turn the wheel to be sure. 

It does seemed to have happened all of a sudden, but I can't see any debris.