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If you cut the map in half, up north, the levers to the east set the holes there hidden. The first lever to your east closes hole 1, the second lever closes hole 2, and the third one closed that hole you face. The levers to the west as you stand there in the middle of the north make all those holes visible which is not what you want. : )
Just the lever I mentioned.
It may be that the fourth lever closes that. Is the fourth lever in the east turned down? You need a key for that. It's a little bit hard for me to tell from that pic whether it's the third or fourth lever but if the third doesn't work, it has to be the fourth.
Check the lion faced reliefs just before the hole. One should have the key. : )