Dave, I just looked at the 10-1506 again and I knew the slotted portion was a little bent (compressed together) so I took a moment to gently pry the sides apart and the gears do fit! Not sure why I didn't do that before. I think it just looked narrower even if I spread the sides apart so I never did. Now I feel dumb! I guess I will use it if my repair of my broken 10-1586 does not work out. Thanks for prompting me to look at it again.