I don't know if your assumption is correct or not. IBut if those are capacitors, they may have a discharge resistor connected across the terminals, so start by looking for that.
No resistor? With the power to the MCC turned off, measure the voltage at the terminals, if those caps are real old, they might not even be in working condition and there will be no voltage present. If there is a voltage present, determine what the caps are connected to. If it is a specific contactor, with the power still off, you can manually close that contactor & let the load discharge the cap.
Few things are harder to put up with than the annoyance of a good example.