Sanitarium hjälp

Saxat från en walkthrough:

(Water Pressure Puzzle)
To solve this puzzle, you must get all of the water pressure to the
Square Fountain. The gauge at the bottom shows your progress. This is
a numbered diagram showing the pieces of pipe that rotate. The N means
there is No rotating piece.
1 4 7 10 N 15 N 19
2 5 8 11 13 16 18 20
3 6 9 12 N 17 N 21
You should put them into the following positions:
1: 7
2: L
3: L
4: Backwards 7
5: L
6: A T pointing upwards
7: Backwards 7
8: A T pointing to the right
9: A T pointing upwards
10: A T pointing upwards
11: L
13: A T pointing to the left
14: A T pointing upwards
15: A L pointing backwards
16: A T pointing to the left
17: A L pointing backwards
18: A minus sign (-)
19: A L pointing backwards
20: A L pointing backwards
21: A L pointing backwards