My analysis is the OC outputs (9,6,8,5) are either :-
(1) delivering too much current, pulling the voltage low. Controlled by R1320 & R1323 (681), R1339 & R1338 (36)
(2) their load is too high a resistance, R1347 (280R), R1343 & R1341 (56), R1403 & R1401 (60R4)
Gilbert cell 155-0078-00
dc