Such a machine that is used to validate {HEAD ~ checks} uses a stepper motor drive to convey {TAIL ~ the check} past the readhead 
Such a machine that is used to validate { HEAD ~ checks } uses a stepper motor drive to convey { TAIL ~ the check } past the readhead
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH