A spline cord positioner is then displaced to {HEAD ~ a predetermined position} on one of {TAIL ~ the side members} of the frame 
A spline cord positioner is then displaced to { HEAD ~ a predetermined position } on one of { TAIL ~ the side members } of the frame
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH