S - This is on the floor at the bottom of the level.

T - This is just under the ledge at the bottom of the level, floating under it.

A - This is inside the small tunnel thing at the bottom of the level, on some boxes at the end.

R - This is on the ledge just before the first ring.

D - This is on the floor just above the first ring.

U - This is on the ledge just under the second ring.

S - This is on the eastern wall just after the second ring, about halfway up the wall.

T - This is on the western wall just below the final ring, near the top.