Some thoughts on the Yeti
From the discussion here and from the videos WDI did on the development of the Yeti, I think we can make an educated guess about what happened to it. The Yeti is driven by hydraulics (probably oil under high pressure), which generate a very large force over a very short distance. From what I recall, the actuators moved on the order of a foot horizontally. The hydraulic system was driven by air pressure out of a series of tanks that would recharge between trains.
This system would then use a series of levers to make the arm move. Think of a lever, where you push hard on the short end and it moves a little, but the long end moves a lot. I believe that's how the Yeti was designed to move.
The actuator pushed a slider up and back horizontally. That slider rode on a linear bearing, and carried a lot of weight and force. It seems like it is that bearing which is failing (the "foundation" of the Yeti). In some cases that bearing is a film of oil that is replenished under very his pressure. As cracks developed, there may have been oil spraying everywhere. High pressure oil can be hard to contain. But this is all conjecture.
So it seems that the Yeti failed because it was improperly designed from the bottom-up. It can't be fixed without a massive renovation, and so it likely would have to be redesigned and rebuilt from scratch. I would guess they would limit motion in the new Yeti to reduce the forces on the bearings, or design something entirely different. In a chat with an imagineer, they once used a backhoe to simulate the motion of a dinosaur, for example.
And so you have it - a design that failed because it was "one of a kind", and a design that cannot be easily fixed. Not a failure, but a case of Disney reaching a bit to far to get the "wow factor" we all love.
This is just one engineer's best guess (and yes, I am a rocket scientist).
