{HEAD ~ An actuator knob} is manually accessible to the user and may be fixed axially to {TAIL ~ the outer housing} 
fixed axially to
{ HEAD ~ An actuator knob } is manually accessible to the user and may be fixed axially to { TAIL ~ the outer housing }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL