After having Kel-Tec twice sending me the newest assembly pin, because I've always had a problem with mine backing out (very rarely) and then telling me to replace the spring, I looked it over and decided that the spring I have seems to have plenty of tension, but the pin has a round radius where the low spot that the spring rests in, meets the high spot and needs to be slightly modified. I put the pin in a drill that I mounted in a vise and using the edge of a 6 inch flat file, which just filled up the low spot space, lightly squared off the radius. This was done under a lighted magnifier, but probably wasn't needed. I cold blued and oiled the pin and now when I put it in and remove it, there is a noticable "snap" to it and I believe that solved the problem. I did not make the part where the spring rests any smaller in diameter, but would have if needed, but didn't need to do so.