Glad to see you are trying to figure out Yambu parts. Yambu is a very beautiful rhythm, not easy and few people actually know how to play it. Congamasterclass.com gives a very good demonstration, extremely clear and much simplified, you should be able to figure it out from those videos, but it will take some time investment and serious concentration with many attempts. The hardest part is to hold the slow tempo and not rush it and turn it into a guaguanco. For us to help you, we need to know more about which part you are trying to learn and what is giving you difficulty.
First, to which of the 8 Yambu videos on Congamasterclass.com are you referring? And which part are you referring to as the "middle part"?