Clock Tower

Go into the central room and down the ladder.

Go through the northeast passage and look for a tile with four colours.

(You can only carry one cog at a time.)

Enter the northeast door closest to the dark grey tile and go as far east as possible.

There will be a cog surrounded by fire. With a bucket of water in your inventory or Ice gloves equipped, pick it up.

Place the black cog on the black spindle, next to the ladder you came down when you entered the dungeon.

Go back to the tile room and head through the door by the red tile.

Go to the end of the passage and grab the cog in the room with the ogres.

Return to the entrance and go up the ladder, to the ground floor and place the red cog on the red spindle.

Exit the clock tower.

Go just south of the Ardougne Zoo, near the camel enclosure, in a corner against the fence, and down the ladder.

Follow the path. Push the wall at the end and pick up the cog.

Climb the nearby ladder.

Re-enter the Clocktower north of you and climb the stairs to the floor NaN, and place the blue cog on the blue spindle.

Return to the basement

Enter the north-west door closest to the white tile.

Follow the western passage and pick up the rat poison.

Go up the middle path, and pull the western red lever on the southern wall to so that both prison doors are open.

Go through the gates and use the rat poison on the food trough, which is on the southern wall.

Wait for the game message 'They seem to be dying.' then head through the west gate and pick the cog up.

Climb up the ladder, enter the clock tower, and climb the stairs to the floor 3.

Place the white cog on the white spindle at the top of the clock tower.

Report back to Brother Kojo, on the ground floor of the Clock Tower.

Quest complete!