TL494 has two error-amplifiers, wired together in a "OR" configuration.
"... With both outputs ORed together at the inverting input node of the PWM comparator, the [error] amplifier demanding the minimum pulse out dominates..." {datasheet}
So Error Amp 1 OR Error Amp 2 can lessen or stop PWM.
In the Sherwood, Error Amp 1 is used to regulate the DC-DC converter output (feedback to pin 1) compared to pin 2 as the setpoint voltage.
But pin 2 is used for another thing.
I think Q520/Q519 ON instantly shuts down PWM. So REMOTE ON turns them off to enable the TL494. Kinda confusing. As long as pin 2 can have its ~4.3V setpoint for Vout.
Error Amp 2 doesn't do much, pin 16 GND and it seems to limit max. duty cycle less than 50%.
You should be able to run the TL494 from REMOTE only (leave BATT unconnected), unless Q520 gets in the way.
It is one way to check signals with DC-DC driver/output transistors unpowered. The pre-driver stage Q508/Q509 should still be working.
The TL494 should just go full tilt, max. PWM trying to bring up the DC-DC output voltage. R556/C521=33.3kHz I would expect.