Remove the harnesses from the loom and lay them flat on a table. Note: it is not necessary to remove the harness from the loom, but if you are putting your heddles on for the first time, it will be easier to make this adjustment.
Before you begin, note which way the groove in the heddle bar hook is facing.
Release the heddle bar from the hook by pulling the slide toward the spring and harness frame and pull the heddle bar out of the way. Using a 1/4″ wrench or pliers, turn the heddle bar hook clockwise to tighten it or counterclockwise to loosen it. The distance from the end of the heddle bar hook to the outside of the harness frame should be approximately 3″.
Be sure to face the groove in the heddle bar hook in the same direction it was in before you adjusted it. Reinsert the heddle bar into the groove and secure it with the slide. You may have to turn the heddle bar hook slightly using the wrench or pliers in order for the slide to slip into place over the heddle bar.
Repeat the process for the heddle bar hook on the other side of the harness.