a retainer curved surface for engaging the actuator lever, {HEAD ~ rolling contact} between {TAIL ~ the retainer curved surface} and an actuator lever surface being caused by depression of the pushbutton 
a retainer curved surface for engaging the actuator lever , { HEAD ~ rolling contact } between { TAIL ~ the retainer curved surface } and an actuator lever surface being caused by depression of the pushbutton
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH