8 switches puzzle in lab

what is the trick to solving these? Endless changing of the facings does not seem to work.

You want all the slots to look filled to solve it.

1) First pick a direction, either clockwise or counter-clockwise.
2) Then pick a slot that is not filled and flip the switch next to it, in the direction you choose in step 1).
3) Repeat that with the next non filled one in the same direction as step 1).
4) When you have only 1 non filled slot left, click both adjacent ones. Then continue to click adjacent ones next to the new pair you created going both clockwise and counter clockwise until those two moving unfilled slots run into each other and you are done.