I have an 18 yr old Glock-17 that I got last week . I dated it to 1992 . I detailed stripped it and cleaned it all very well . It shoots good and extracts and feeds well . The slide-lock bar (take-down lever) was a little messing looking even after cleaning . All in all it functions great . What should I replace because of age ? I am going with the slide lock lever and the recoil spring assembly because the guide rod inside it is warped pretty bad as compared to my other Glocks . Also I am getting new firing pin couplings (little plastic things that hold the spring on ) What else should I get that normally gets replaced with age ?