The force of the tumbler spring then pivots the tumbler into {TAIL ~ its assembled position} where {HEAD ~ the detent} is engaged with the retaining ledge 
The force of the tumbler spring then pivots the tumbler into { TAIL ~ its assembled position } where { HEAD ~ the detent } is engaged with the retaining ledge
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH