I am posting this question here and under the Ranger Boat forum to increase the views. Over the weekend I took my 2000 Ranger 518 and Ranger Trail trailer out of the garage for the first fishing trip of the year. Hooked up the trailer as usual including putting a trailer-lock on after closing the coupling. Halfway to the lake I hit a pretty big dip in the road and the next thing I know the trailer has jumped off the ball of the hitch. Fortunately the safety chains and the emergency trailer brake wire kept this from being a disaster. My question, why did that happen? I would think (since I've had the boat and trailer for 15 years and this is a first) that the padlock through the pin hole of the trailer coupling would have prevented this from happening. Is there some adjustment I can make to the receiver that will prevent this from happening again? Needless to say I am a little spooked by this near-miss.