Trouble with the lift screw for the beetle

I tried. I really tried. But the Archimedes screw lift got the best of me. I thought everything was looking good. The screw lift is more than six-feet tall. A lot can go wrong in something that long. If the screw is not true, it will not lift the marbles properly. Here is a photo of the screw before being attached to the motor.

Next, I attached to motor and gear mechanisms to the frame of the bug. Alignment is key. I used two gears, so the screw would turn counter-clockwise.

In the end, the screw lift was a little bit off. The marbles worked their way up the lift about halfway, before tumbling back down. So frustrating. But, this is a learning experience. Time to try another way.