Here is the schematic with the board reference designators for the components in question:
The blue resistors and 3 ceramic capacitors (each should be about .39uF, not the 5pF default shown on schematic) are part of the voltage divider network on the input side to the hybrid board that drops the pack voltage down to a lower level compatible with the op amp range. Those marked as 1 in your photo are not involved as far as i know.
There is also a bleed-down network in the path shown with FET2. All those parts need to be checked too if possible just to rule out possible fault paths.
There are parts on the bottom side of the ISA hybrid board that could be checked if that board was desoldered from the main board. i don't have a schematic for the hybrid board but it would be worth checking everything that could be measured on it. The next level of diagnostics would be to power up and test the ISA board on the workbench.
Also on the op amp i measured 100k between pin 6 and pin 2, and 258k between 6 and 3.
If the passive voltage divider network checks out okay, then my guess is the issue is likely on the hybrid board.