Does the arm move at the box as soon as you turn the wheel back and fourth? Or is there still slop between the pin and worm gear slot. Did you check the pin at the top, center and bottom to see if the worm was wore in the center? I can make you a larger pin but if the one I sent you is tight at the top and bottom then a larger one would not work as it would bind before you could turn the front as far as it goes right or left. The one I sent you was the laSt one out of a batch of four. The other three worked. Lets make it work one way or the other. Might take a different gear and shaft.
I was in New Boston and Decalb Texas on my way to Idabel Oklahoma at the end of last week. Long ways from you I would guess.