{TAIL ~ A plurality} of rollers are fixably and independently mounted in each of {HEAD ~ said channel members} 
{ TAIL ~ A plurality } of rollers are fixably and independently mounted in each of { HEAD ~ said channel members }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD