Key stuck in the on position?

Key stuck in the on position. The locksmith came and put in a new ignition (after showing the old broken one), programmed the new key and then could not get the key out. He took out the ignition switch fuse and the key turned back to the lock position and came right out. He said he doesn't know what the problem is and to take it to the dealer to get it fixed. It was bought used, and the guy doesn't know anything about it. I am being told mixed things about spraying wd 40 in the switch some say the locksmith didn't lube the switch when he put it in. Others are saying don't do that to crush up pencil lead and rub the key down with it. I don't want to have to pay $700 again for a $20 part. So, I need help please.