{HEAD ~ An activation button} exposed through the top of the assembly is depressed to actuate {TAIL ~ a switch assembly} which, in turn, actuates a drive mechanism 
is depressed to actuate
{ HEAD ~ An activation button } exposed through the top of the assembly is depressed to actuate { TAIL ~ a switch assembly } which , in turn , actuates a drive mechanism
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH