No, the turn buckle (I may not be using the right word for it) is the gizmo with the wing nut at one end. You can turn the buckle part to shorten the length/distance between the two s hooks which will apply more tension to the brake band so the warp doesn't slip
But if you have so much tension your shuttle won't pass through the shed, perhaps you have too much tension on your warp?
Good posture and position in the loom for all the stages in the process of weaving is extremely important. The more people present this information, the more people will benefit from it. Thank you Rebecca for doing the presentation at Convergence.