Correct opening and closing of shaft barb is at the base of a secure catch.
After fish has been hit and passed by the shaft, it can happen, in rare but critical cases, that the barb re-closes and the shaft slides away from the prey, often even important fish. This can happen with greater probability when the fish is caught from below, as the weight of the barb makes it re-close. A fast and clever adjustment, acting with pliers at the base of the barb, permits to maintain the correct opening of the barb, but to tighten the final part, avoiding easy re-closure. In the below video the procedure to follow and the final result. Total time needed? Less than a minute!