Cobra Trailer Jam-nuts (loose)

Don't know why, but the last 3 Cobra trailers I have seen all had very loose wing spar jam nuts. When a wing is rolled in, it's spar passes under a horizontal cross bar and when the tip is lowered into the floor saddle, the spar rises slightly to firmly come to rest under the horizontal cross bar...............everybody still with me? OK, this cross-bar has 2 big wing nuts on top and the idea is to hand tighten these wing nuts so that the cross bar rests firmly on the spar butt. If not, the wing will sway side to side on the road.............Got the picture? What keeps your wing nut setting in place is the jam-nuts under the cross bar............and these puppies are loose .......all of them on the last 3 trailers I have inspected!
FIX, hand tighten all wing nuts so that the cross bar rest firmly on the spar butt AND then tighten the jam-nuts located on the under side of the cross bar. Let me know what you find and any reason why these jam nuts are loosening? I'm sure they were all tightened when the ship was originally fitted to its trailer? Or Were they?
JJ