I need advice on how to find and select a replacement rear site for an older S&W Model 41 22LR target pistol. This model has the older style rear site, which S&W discontinued years ago. Four small parts (sight elevation screw, sight wavy washer, sight plunger, and sight plunger spring) are missing, and I cannot find replacements at any of half a dozen parts shops nationwide, including S&W. Thus, I need a complete replacement for the sight. What should I look for, and where? If I find the part I will have local gunsmith install it, unless the source also will install. Should I consider having S&W replace it with their own current-style M41 sight? Can anyone confirm whether old and new are interchangeable on the old model? Thank in advance.