Although Excam officially went under in 1989, your Pistol may still have been one of theirs as they did try, unsuccessfully, to re-organize.
As for the Roll Pin that holds in the Sear, measure the hole for it, with the blunt end of a drill, and get another Roll Pin, that size and put it in, with the appropriate sized Roll Pin Punch. You can also use regular Pins of the appropriate size.
A well stocked hardware store will have Pins and Roll Pins.