None of the BW transmissions we have owned had a lock down feature. Even if they did, there are other forms of transmission failure than clutch plates--we had, and have seen several others with failure of the output shaft. In our case it was caused by hitting a 3/4" steel "Tuna" net cable. This not only damaged the output shaft, but also an engine mount. I got the engine out of gear, but the boat was still doing 7 knots when the prop hit, and the 60,000 lb boat was spun 180 degrees. Bob Austin