About a week ago (thereabouts), in the early hand ejectors section (1896 to 1961), there appears a thread titled "triple lock help". Therein, "Hondo44" did his usual thing----and presented a doctoral dissertation----this time on what you said: Where to buy parts.
If one or more of those listed can't help you, you very likely can't be helped.
"...S&W 2nd model 38..." covers several different models and parts suppliers will need a better definition of which model you have, however many of the models can use the same pivot screw, depending on frame size, etc. Ed.