control circuit means responsive to {TAIL ~ said signals} for operating {HEAD ~ said electrical select device} to select one of said synchronizing devices 
control circuit means responsive to { TAIL ~ said signals } for operating { HEAD ~ said electrical select device } to select one of said synchronizing devices
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH