The 'top down' diagram below shows the location of the correct symbols.

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                                 Secret: x
                      On a ledge behind the blue room.

             |-----------|      |----[x]----|      |-----------|
             |           |      |           |      |           |
             |           |      |   Blue    |      |           |
             |           |      |  (Lower   |      |           |
             |           |      |   Level)  |      |           |
             |           |      |           |      |           |
             |-----------|      |-----------|      |-----------|



             |-----------|      |-----------|      |-----------|
             |           |      |           |      |           |
             |           |      |           |      |           |
             |           |      |           |      |           |
             |           |      |           |      |           |
             |           |      |           |      |           |
             |-----------|      |-----------|      |-----------|
 Walkway          | |
 mentioned -----> | |
                  | |
             |-----------|      |-----------|      |-----------|
             |           |      |           |      |           |
             |    Red    |      |           |      |   Green   |
             |   (Top    |      |           |      |  (Middle  |
             |   Level)  |      |           |      |   Level)  |
             |           |      |           |      |           |
             |-----------|      |-----------|      |-----------|
                                   |    |
                                   |Lift|
                                   |    |


I would go for the blue symbol first from the lift. Run off, run off, run off
straight down the center line. (By "run off," I mean just run off the edge of
the first walkway and hold forward to fall to the next roof. Then run off the
edge of that roof to land in the doorway of the room with the blue symbol.)
Then go back down the center line on the blue level roofs. (Turn around, and
from the blue symbol console, jump from the doorway up to the next roof. Then
jump from that roof to the next on the same level.) At the end turn left, and
jump up into the doorway of green room for the second symbol. Then turn
around and jump up to the green roof opposite the doorway, and jump across to
the green roof ahead. Jump up to the walkway above, turn around and enter the
room with the final symbol. Exit that room, and jump from the walkway to the
roof of the green room nearest the lift. Jump up to the ledge around the lift
and ride the lift up.

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