Really? I think there were some transparent boosters placed on the tube. Changing their values ​​or adding new ones at the stacked positions might fix the problem.
However, this issue hasn't occurred in my environment, so I can't say for sure.

Also, there are some stacking positions on the outside of the tube, such as near the net.

I hope this is helpful.

My marbles keep getting stuck at the tower in the little tubes. How do I fix this?

Thank you for your comment! Unique! That's the compliment I'm most happy to hear! And thank you for enjoying it!
(Is my English right?)

Very unique map you made here. I like it