The Janome walking foot doesn't have a claw on the end of the little arm - it's just a straight bar. I also have a Janome and mine is just the straight bar that rests on the needle screw. However, on mine, the arm isn't resting on the head of the screw, it's more on the shank/straight part of the screw. How often are the needles breaking/coming loose? Can you check the tightness of the screw every so often to see how often it comes loose?