And when you turn the cable around hold the trainer switch while powering the TX.
Perhaps you never really bound your system in the first place.

Back to your servo question, just put the servo cable directly into your receiver in the same slot your esc is in now.
If I saw it correctly it was connected to the throttle channel which is the lever that you can set to a specific setting without it selfcentering.

(I do apolagize if I sound like I'm talking to a child, I just want to make it as basic as possible for I do not know how much experience you have with RC equipment.)