Spoiler: Pull the lever at the right top most. It's a bit tricky though. Then pull the levers in the right order of bulbs that lights on. First there's only one bulb, pull that. Then it asks you a 2 bulb, it goes on up to 6. You just have to memorize which bulbs light in what order. If you've quit the game, don't worry, there's a save system.
Spoiler: Pull the lever at the right top most. It's a bit tricky though. Then pull the levers in the right order of bulbs that lights on. First there's only one bulb, pull that. Then it asks you a 2 bulb, it goes on up to 6. You just have to memorize which bulbs light in what order. If you've quit the game, don't worry, there's a save system.