Let Trico carry you around the corner of the hall and knock down the drawbridge door.
After a brief cutscene, stay on Trico's back as he carries you across a series of pillars. He'll come to a stop in front of yet another stained glass eye.
Climb down Trico's tail and into the pillar he's standing on. Cross through to the other side (the way Trico is facing) and start climbing down the ledges there. Drop to the rope and start walking across.
From the ledge at the other end, jump up and grab onto the ivy. Follow the ivy up and to the right onto the bridge above you.
Head up the stairs and drop through the gap to the inside of the tower. Make your way around to the right to find another rope.
This time doesn't go as well, but at least you don't need to get rescued. Climb up the rope to the top.
At the top of the rope, jump up to the ivy and climb it up even further. The ledge you're looking for is on the right side at the very top. You'll find another rope here to walk across. In the middle, you'll find the lever that allows you to drop the eye.
Climb down the now unbalanced arm, then onto to chain. Take it down to the next mobile arm. Use the mobile arms to get into position to jump down onto Trico.
Let Trico carry you up from platform to platform until he freezes again in front of another stained glass eye.
Climb off of Trico, then use the ledge on the left to continue up the tower. Squeeze to the left of the rubble on the next set of stairs. Use the ledge again to continue. Turn right as soon as you reach the stairs.
Climb out onto the wooden beam and disconnect the eye. This also does not go well for you.
Wait for Trico to get into position below you on your right, then drop off the handle. This actually took us a few tries, and it's a little unclear why. Just make sure Trico is all the way down at the end of the stairs and paying attention to you.
Once Trico has saved you, he'll start to climb up the tower again. There's not anything for you to do for a couple minutes, so don't jump off.
After a series of heart-stopping jumps, Trico will climb onto the cliff above the tower. At the top, you'll meet another trico. This one is kind of a jerk.