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