When you are ready for another round of room rotation puzzle action, pull the switch. Move to the right and wait for the crate to drop. When it does, wait for the room to rotate a little more and push it to the right until it is on the edge of the platform. Use the crate to jump across the gap before the small gate comes down or you will be crushed by the boulder we jumped over earlier.
Once you are safely on rotation-free ground, continue to the right, jump onto the cog and ride it to the right. Jump off and continue until you see a lone figure sitting on the ground. As you approach it, a brain slug will ambush you and force you to run back the way you came.
Jump back across the cog and up to the higher platform; continue until you reach the beam of light. Run back to the right, over the cog. You will notice that the room has now transformed into something quite different.