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