Jim Keenan has given you very good advice. I speak from experience as to the difficulty of finding parts and then working on these revolvers. Parts might be found, but there is no guarantee they will work, presuming you can get them in place and the piece re-assembled. I broke two flat springs before I got mine working, but I may never fire it.
The best, and only book about these fine early Colt New Army & Navy revolvers is: A Study of Colt's New Army and Navy Pattern Double Action Revolvers 1889-1908 by Robert (Bob) Best. He used to hang out on the Colt forum. I believe he was working on an update to his 2004 book.