dryer will not turn off

Dryer runs and heats OK, but it will not turn off even though the timer counts down to near zero. It will also not turn off in the "automatic" dryness mode. If I move the timer knob a bit more to the off position, it will shut off. It seems like the timer gets stuck right before the shut off position. Can I lubricate it or do I need a new timer? Or, is there another problem? Thanks.