1955 buick doors

hello the door lock mechanisms on my 55 buick are constantly falling off the inside of the door handle in the door and falling inside the door can someone tell me what type clip or pin is used to hold the arm to the inside of the handle

 

Your clips may be stretched or lost their springiness (is that even a word ? ), installed incorrectly, the handles worn, or you've got the wrong clips. GM changed to a larger clip in 1948.

You can get new, correct clips here....... http://www.parts123.com/parts123/yb.dll?parta~partsort