My Kenmore dryer works intermittenly. It started with the moisture sensing section on the timer knob rotating and setting off the buzzer in about 3 minutes with the clothes still wet. When I switched to the timed section of the timer knob it sometimes works fine, but sometimes stops and sets off the buzzer at random times with the clothes still wet. I checked and the vent is not plugged, and the gas burner is working when I check it. Do I need to replace the timer, or could there be something else wrong?