A stop member for an operator chain in a chain operator, wherein the operator chain has a width, rivet holes and rivets, constitutes a pin arranged in a rivet hole not occupied by a rivet in the operator chain, wherein the pin has a length exceeding the width of the operator chain. The pin can be cylindrical with a diameter corresponding essentially to that of the rivet hole, and the diameter of the pin can be slightly smaller than that of the rivet hole, so as to be loosely held in the rivet hole.