But the bad luck is that, even if it was, this was not a unit designed for servicing. No plate amp on the back to unscrew. You have to cut wires to remove the baseplate, then unsolder more to get the amp module out. Fergit about easy probing with a scope whilst runnning! What were they thinking*?
At this point the temptation to take the speaker out, shine a torch in to look for the relay and give it a good tap before cycling it a few dozen times is high!
*The service manual is an oddly specific combination of specific instructions for dealing with known faults and arm wavy faff that suggests bar those you give up and throw it in the skip
.