In {TAIL ~ some positions} three or four rollers 91 and 92 will engage {HEAD ~ the cam gears} 
In { TAIL ~ some positions } three or four rollers 91 and 92 will engage { HEAD ~ the cam gears }
OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD