a helical spring held within {HEAD ~ the housing}, the helical spring biasing the slider against the second portion of {TAIL ~ the arm} 
a helical spring held within { HEAD ~ the housing } , the helical spring biasing the slider against the second portion of { TAIL ~ the arm }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL