Is it frozen? Mine would not turn at all so I gave it a shot of wd40. That did nothing. A friend of mine gave it a shot of "kano-AERO KROIL" (says the oil that creeps). I was very skeptical. To my amazement the knob turned like it was brand new. I have since used it for numerous rusted stuck bolts and it has not failed me yet.
Hope this helps.
Richard