The components passing over the optical inspection window may be inspected on {HEAD ~ the fly}, without requiring stoppage of {TAIL ~ each} of the components thereabove 
The components passing over the optical inspection window may be inspected on { HEAD ~ the fly } , without requiring stoppage of { TAIL ~ each } of the components thereabove
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH