Was at an equipment dealer today. A fellow came in with an F-350 and a gooseneck trailer. He was picking up a Yanmar 5 ton excavator. He started up the ramps and when he got to the trailer, the hitch post came off the receiver ball. Fortunately he had his safety chains fastened and they held the trailer. The trailer went forward a foot and the ramps came up in the air. The dealer got some jacks and lifted the trailer to let the ramps back down. They then pulled the truck forward slowly to get the hitch back over the receiver and about 5 of us put all our weight on the trailer nose to get it secured to the receiver. No damage to truck, trailer or people. Fellow said he must have forgot to secure hitch after dropping it on the receiver ball. Reinforced in my mind the need to be precise and thorough when doing any trailering. If one of those safety chains was weak & broke that trailer would have ended up in the cab.