I can only partially bend notes on harmonica, how might I do it fully?

The secret is in the vibrator hand action, speed and length of the movement back and forth away from your mouth (or the flapping motion if you are wah-wah-ing) and the volume of the resonator cup made by your holding hand. On top of this the volume and power of your breath over the reeds adds the final touch. You need to practice, concentrating on each component, and sooner or later it will all come together.