Estes Star Seeker BT-50 Upscale (Tri-Pack) Kit #0866, Part 3, Engine Mount

The tube was slit for the upper bend of the engine hook. A  installed motor will extend 1/4" out the bottom end of the tube.

One of the laminated rings got rotary punched for movement of the engine hook. 

For a bit more strength, the upper ring was set right over the upper bend of the engine hook. 

The lower notched ring was placed 1/2" from the bottom of the motor mount tube.

Notice the ruler. The low (and top) end starts at the zero point. Usually rulers have a 1/8"extension before the 1" point  starts.  

A wrap of electrical tape holds the engine hook and allows flexibility.

TIP: Electrical tape won't deteriorate over time like paper masking tape will.