My opener hums and won't open the door.

Your opener hums and you don't like the tune? More than likely it's the capacitor. This is found inside the opener. Unplug the opener. Take the cover off. Get the information from it (The capacitor is a cylinder shaped object, usually 1-1/2" in diameter and 3" long). You will need the MFD number and the VAC number. It is important that the capacitor is replaced in the same manner with the writing facing the same direction as the one removed. If it is a Sears/Chamberlain/Liftmaster opener and if there are white shavings beneath the will need a gear kit.