Parts are still available - if not in gun or online stores or parts sellers, a gun show will usually have a few vendors selling new and or used parts for vintage models. They are a welcome sight for those for us heavy into vintage Smith's & Colts's. I made sure (about 20 - 25 years ago) to have enough of the common wear parts on hand to not worry for the rest of my life.

If you are not wanting or willing to learn how to repair them yourself, I suggest asking around (extensively) to find a very competent Gunsmith. Don't just hand them over to the first one you meet - make sure by multiple recommendations of people you trust that the GS you use knows what he's doing! I have seen way too many "butcher jobs" by so called GS's! I am sorry to say, there are more "butchers" than skilled craftsmen who take pride in what they do. A good GS is quite a find these days!