My father in law has a N frame 357 that he acquired used from the original owner in what he believes was around 1963. The guy he got it from was a target shooter and had done some filing on the sear to lighten trigger pull. All was fine for many decades, but now the revolver has developed severe push off. The lightest touch to the hammer (or the trigger for that matter) will cause the hammer to fall when cocked in single action. The double action sear works fine.
What parts do I need to source to correct this properly? Hammer spur is .500" wide. Do I need a hammer and trigger, or will a hammer alone suffice?
Can parts from a later model N frame be used? How will replacement parts effect value?