The insert is pushed forward into the open jacket which is pushed away from {HEAD ~ the opening blade} permitting {TAIL ~ closure} by gravity 
permitting
The insert is pushed forward into the open jacket which is pushed away from { HEAD ~ the opening blade } permitting { TAIL ~ closure } by gravity
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH