By {HEAD ~ means} of {TAIL ~ such an arrangement} intermediate positions of the guide disc can also be effected, while a very compact configuration of the positioning unit is obtained at the same time 
of
By { HEAD ~ means } of { TAIL ~ such an arrangement } intermediate positions of the guide disc can also be effected , while a very compact configuration of the positioning unit is obtained at the same time
OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH