user in this condition the ball drops from the drop mechanism this condition corresponds to those in fig3 b described above and fig6 c to be described later in an actual application there is a further situation where the lowermost ball drops within the lower housing 42 through the stopper ring 46 but will not drop from the lower housing 42 as shown in fig6 b this condition will be explained later first the condition is explained wherein the lever is not operated that is the ball is maintained in the lower housing 42 as shown in fig4 a and 5a the ball stopper ring 46 is not positioned at the center but is positioned close to either one of the sides of the lower housing due to the spring force of the spring 54 thus the center of the ball stopper ring 46 and the center of the lower housing 42 do not match which makes an overall size of the ball passage smaller than an outer diameter of the ball accordingly the ball cannot drop because it touches the upper shoulder of the ball stopper ring fig6 a when the lever 180 is moved as shown in fig4 b.