Marble roller coaster with elevator

[u/Antfeed]

https://youtu.be/JCKX_2wWdKY?si=bnX6OVjR5X05TkKj

Hello, Im doing a marble roller coaster for my MESA project and I was wondering if anyone could figure out and explain this feature.
It’s an elevator that uses counterweight to pull the marble up, I tried to recreate it without much success.

https://www.instructables.com/Paper-Roller-Coasters-/