Screws for older style Dive Rite fins

[tomcatbubba]

Does anyone know what size screws are used in the old style Dive Rite XT fins? These were the first generation that had the spring from the heel strap held via a long threaded female pin, with a small machine screw that threaded into the pin to hold the assembly together. I lost the screw on a recent dive and my local hardware stores don't sell anything that small.

Thanks!