Hey, thanks for taking the time to try it out! :D
After you get the track control prod, take the mine cart back to where you got it from the start. Next, get on to the mine cart again, like you're riding it back to where the creature is. as you're riding, your character will automatically place the track control pod into the lever base and flip the switch. The tracks will then switch over and take you to the west tunnel.
Hope that helps! Let me know how your progress is and if you need any more help I'm always eager to assist.