I've purchased 4-40 and 2-56 screws and neither are the correct size for the threads in these atlas spdt switches or the threads on the switch machines themselves. it looks like there are just inbetween 4-40 and 2-56. Can i get these screws at a hardware store or do i have to order some "special" screw? Thanks PS. I am almost done running the wires for my turnouts, only 3 more to run then i get to screw them up and be surprised when none work .