Looking at your diagram, I would guess that the brackets hook to the front and rear of the wooden carrier in some way and are spaced left-to-right so the carrier can't slide around. This suggests that there has to be some way to release at least one of the hooks (likely a front hook) to get the hooks around the carrier. I don't have one to study so can't help more than that... photos will be welcomed if you do find one to work from.
Looking at the diagrams, the radio, power supply and antenna tuner all look to be a later generation than WS19. I don't know whether the carriers remained the same or changed with the generations of radio.
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