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