I had the exact same problem with a trailer not wanting to let go, so I called my dad and he suggested cranking the legs as far down as you can to take as much weight off the 5th wheel as possible. Then lower your suspension and try pulling out gently at first, if that doesn't work be more aggressive with it.
Just make sure to lower the trailer once your out for the next guy.
I ran into the same situation this past summer I couldn't get my Tractor to uncouple from my Flatbed. Lucky I was in the yard so I got the mechanic to help me get it uncoupled. The Mechanic that the grease gets dirt and crud embedded and it fowls up the locking mechanism. He scraped out the contaminated grease sprayed the locking mechanism down with fluid film and put fresh grease on the 5th wheel. Now it's good to go every time I have to drop my trailer I'll give the 5th Wheel the once-over.
Bobcat Bob posted:
I ran into the same situation this past summer I couldn't get my Tractor to uncouple from my Flatbed. Lucky I was in the yard so I got the mechanic to help me get it uncoupled. The Mechanic that the grease gets dirt and crud embedded and it fowls up the locking mechanism. He scraped out the contaminated grease sprayed the locking mechanism down with fluid film and put fresh grease on the 5th wheel. Now it's good to go every time I have to drop my trailer I'll give the 5th Wheel the once-over.