The object here is to pull down the correct combination of levers to create a long enough piston to push the gear until it is no longer visable.
If you're on the right track, pulling down a lever will make the piston longer. But if the piston gets shorter after you've pulled down a lever, at least one of the levers is wrong.
Label the handles 1 to 7 from left to right. Pull down handles 1, 4, 6, 7.