The disk drive mechanism of {HEAD ~ the sensor dispensing instrument} is operated by pressing a button which activates {TAIL ~ a motor} 
The disk drive mechanism of { HEAD ~ the sensor dispensing instrument } is operated by pressing a button which activates { TAIL ~ a motor }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL