Well, I know this ended a while ago, but I was able to get a look in the control room for indy with the cameras and all the other fun toys. My friend who was operating it showed me exactly how the WHOLE ride worked. I see you guys understand the doors but you are a little bit wrong on the ball part. The ball is on a horizontal shaft which is connected to vertical rods with wheels at the bottom that are on a track. The ball is always turning even without an emv in sight but it moves back when it's resting and when it's doing it's show for the emv, it slides forward a little that matches the speed of the turning of the ball on the shaft. The days that have been hard for you to see the ball were because the room around you wasn't moving forward to simulate the backing up. This means that the lights positioned to shine on the ball are blocked by the top of the "moving room". When the room moves forward, a hole in the top of it matches the static lights on the real ceiling so they can shine through to light up the ball. I have confirmed all of this by taking multiple trips to the control room and bringing flashlights on-board with me. But remember, on the days you can't see the ball very well, the romm is not moving forward, so you will not notice the effect of backing up.
I know this is probably very confusing but bring your own flashlight and you will notice alot more and maybe even sweettalk the operators to let you see the controls.
-Burt