Understanding opamp feedback loop with parallel paths
Important parts of the circuit diagram are cropped.
The 500 ohm resistor is a level-translator programming
component, and current through it (to ground) modulates the
collector currents of the MJE340 and MJE350 which are
level translators.

Positive power supply and negative power supply current to
the op amp ARE OUTPUTS here, and mismatch according to
the current to ground through that 500 ohm resistor.  The
voltage difference across R8 is the difference of the
direct (from op amp) output and the driven (from those
pullup/pulldown lines that go off-page) secondary output.

Whatever current-boost the circuitry outside this part of the
diagram shows, is important; if there is gain due to
resistor ratios in current mirrors, the 100k "R10" component
might be a dominant feedback signal.  Current through R8 and
R7 + C1 into the output pin is another feedback (which
modulates the op amp power currents into the secondary output).