I swear it sounds like you've got the wrong foot for your machine, somehow. It should go on easily: fork onto the needle clamp, cone into the foot, swing the little arm down that holds the foot on the cone. It should be totally stable then. If the sole is on right, the needle shouldn't be hitting it. So if it IS hitting the sole, it's gotta be the wrong foot, eh? Which Bernina do you have? Happy to see a PR member here on QB, sorry you're having this trouble.