My Challenge to Make a Marble Run Machine - Failure

I've been making a marble run machine filled with spirit. Contrary to expectations, the machine in production worked well. Yes, unfortunately, it's past tense.

While rotating the machine's handle in a chipper mood, I found a malfunction. What!? It was supposed to work well. What has happened?

 

My husband and I were both surprised and scrutinized the movement. We guessed the reason for failure. For the time being, we tried to fix it but couldn't fix it completely.
It worked well when I rotated the handle slowly, but once I rotated faster, some of the balls on the machine started falling. It still worked, yet I wouldn't say I liked it. Therefore, I decided to make another part again.

One of the thick boards that was supposed to be a pot mat turned into a gear, and then, after finding the failure, it went back to a pot mat again. I still have some thick boards, so I'm going to use them to make a replacement part.

It's going to be a long way to go.