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