This video explains how to position and orient the remaining 4 centers. The first 2 centers I place are the Red and Blue centers, which must be oriented properly. Red/Black/Blue must have a clockwise orientation.

Next I go on to place the last 2 centers. If you decide to SKIP TO THIS PART, you can fast forward to around 5:15. I explain how to:

1) Try to keep on forming 1×4 blocks and join them together
2) If you cannot create any more 1×4 blocks, you can “kick out” pieces (1×4 blocks) in order to get as many center pieces onto their proper side.
3) Use the center switching algorithm.

Because the center pieces can be on different layers, I find that memorizing the algorithm as a sentence is easier.

Sentence:
Down Over Down Over
Up Over Up Over

We must position the IDENTICAL pieces we want to switch in the same RELATIVE POSITION. I generally prefer to place them in the upper left of the 4×4 center.