Happened to me once too. I thought the detent pin flew out. Had to look all over the floors, my books cabinet, sofa and etc. Gave up and took a deep breath telling myself "#*$?@?@*$/@". Suddenly my eyes saw something tiny and shiny UNDER my vise. LOL.
Another incident, i accidentally bent the safety selector spring. Called PSA the next day and asked if they could waive the shipping fee ($6) over 1 only spring which costs only 99c. They looked up my shopping history and decided to send me one FREE. Lol.