OW,
I don't have a schematic of the Colt. I have taken them apart a few times when I had a project of my own. The lever return is a small flat V spring, similar to most SxS guns. The firing pins float, no springs. Or at least neither of the two guns I have had springs. The workmanship inside these guns is top rate, inside and out. There is not a lot of mystery in there. Flat springs etc.
Cimmaron sells or sold a Chinese copy that is close enough to get parts from. Finish and fit them as needed.
Good Luck!