Everything that has an end, has a beginning...
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if you're just missing it, then look up as you're going into the portal. It should give you more of an arc
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Figured out another method. For this one the lower moving wall is not useless.
1)Get to the point that you have the lower wall move out. Put a portal (blue?) on the upper moving wall's right side. Place a portal (Orange?) on the floor and jump into it. Your goal is to exit the top portal and land on the top of the lower moving wall. It's a little challenging, but it makes the next part a cinch!
2) Jump off the wall and fire a portal at the ground where you fall. Couch as you go through. This gives you enough momentum to reach the upper deck! Make sure you keep holding forward!
Shifted to this and made it in one try!
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Another way, that makes it easier:
Put the portal on the higher platform, but walk through carefully so you can stand on the other one that came out. Then, jump off the lower platform, giving you just enough extra momentum to make the jump easier. Also, the top portal should be a little off-center to the right, facing it.
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