1997 Chevy Malibu Malibu occasionally refuses to steer to t

I have a 1997 Chevy Malibu. Today it developed a problem that it does not always want to steer to the left. Steering wheel turns to the right easily, and to the left easily most of the time. But every once in a while I cannot force the steering wheel to the left. No matter how hard I try. But if I turn it to the right, it will then go back to the left just fine. No power steering fluid leakage. No broken parts that I can see. Just doesn't always want to turn to the right when I need it to.