Resistors R located between {HEAD ~ the non inverting terminals} of op amps 68 and 70 to voltage sources V2 provide balanced impedences to {TAIL ~ the op amp terminals} 
Resistors R located between { HEAD ~ the non inverting terminals } of op amps 68 and 70 to voltage sources V2 provide balanced impedences to { TAIL ~ the op amp terminals }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL