Essex primer pump part

[9Abuilder]

I am rebuilding an Essex manual primer pump, K2403-4. One of the two small screws at the bottom of the pump fell apart as I was loosening it from the valve assembly. This screw holds the tiny ball bearing and spring at the portal opening. I?ve looked everywhere for a replacement screw with negative results. Does anyone know where To locate one of these screws? Like me, the older it gets, the more brittle.