For your consideration, here is an Alvin Pantograph Resting Post Stylus Piece Spare Replacement Part.  I don't know the offical name for it, but that is what it does.  It was part of a 21 Inch Long Pantograph, no. PA306.  It may fit other Alvin model pantographs.  It is 1 1/2 inches long.  It is in nice shape.  It will be mailed in a box for protection.  Item pictured is the actual item up for sale and comes from a non-smoking household.  (404.832h-.4bx3)