11. The improvement of claim 1 wherein the receiver has an inwardly directed stop and during assembly of the insert with the receiver, the insert projection must be forced against and pressed to a position beyond the stop prior to being in sliding engagement with the pivot track, the stop capturing the insert projection in the pivot track.
11. The improvement of claim 1 wherein the receiver has an inwardly directed stop and during assembly of the insert with the receiver, the insert projection must be forced against and pressed to a position beyond the stop prior to being in sliding engagement with the pivot track, the stop capturing the insert projection in the pivot track. 12. The improvement of claim 11 wherein the insert is top loaded into the receiver with the projection insertable into a groove formed in the receiver arm, the groove running parallel to the shank axis.