Step 6: 4. Install Engine Mount
4.1. Apply glue to the edges of the centering rings of the motor mount. See the video below for more details.
4.2. Slide the Assembled Engine Mount into the bottom of the Body Tube with the Engine Hook towards the bottom until the bottom of the Engine Mount Tube is even with the bottom of the Body Tube.
4.3. Glue the joint between the lower centering ring and the rocket tube.