The switch is under the instrument panel, attached to the side of the steering column. There is a rod that runs from the key barrel down to the switch. Turning the keys moves the rod back-n-forth. You may be able to loosen the screws on the switch and adjust or yuo may find you have to replace the switch.
You still haven't mentioned what the symptoms are, so I'm not sure what else to tell you. Is the symptom that it intermittently doesn't crank when you turn the key? If yes, try starting it in neutral which would point to a bad NSS and not the ignition switch.