[Jim K]

My memory cells are working overtime, but I think there is a plunger on that spring and the pointed end of the plunger fits into a groove around the pin to hold the pin in. You will probably have to make a pin, not just use a roll pin.

(This is the same idea as the way the bottom of the mainspring retainer pin fits into the annular groove in the mainspring housing pin on a Model 1911 pistol.)

Jim