Turing Tumble Community

Puzzle 38 help!

Hi all, new to the community, so please bear with me!

38 has me completely confused. I understand the objective, just totally struggling on getting it working correctly. I don’t want to look at completed solutions just yet, so any tips? What am I missing?

Thank you

You have to send a ball in turn to the 1st bit, then 2nd bit and 3rd bit. But you don’t know if the balls will be coming from the red or blue side, so you have to handle both.
Good luck!