Board-to-board PCB connector on NAD amplifier - how to detach?

I am taking apart a NAD T750 and it has a vertical volume circuit board that connects directly to the (horizontal) main circuit board. There are two board-to-board connectors to detach and one of these easily pulls up without any manipulation but the other one does not budge. On another forum it was suggested that I tried pulling on what looks like latches on the sides while I pull the board up, but that part of the connector does not seem to move at all. If anyone has come across this type of connector I would appreciate any advice!


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