Baldwin Sharknose A unit parts

[MopacMan]

I am trying to locate the mounting screws for attaching the rear steps to the chassis of an O scale Baldwin Sharknose A unit.  Due to my carelessness, the missing screw is impossible to find in my train room.  Attempts to find a compatible screw at a hardware store/big box store has been futile.  Any suggestions would be welcome on where to find them?