With my old trailer, I used to have to spray silicone on the seals at the the blade closure (gate) once or twice a year. I would have to get a can of silicone with the straw to get it in "around the bend". Let it sit for a couple of hours, and Bob's your father's brother...
Haven't had this problem with the new one yet, hopefully for a while, and not sure how easy it will be to get to the gate.
Hope you get it unstuck without too much effort.
2011 Jay Flight 26BH
2007 Chevy Silverado Classic, Ext. Cab, 4x4, 5.3l HO (L33), Z71, HD Tow Pkg, 4.10 G80
Hopkins 'Agility' Brake Controller
Husky WD Hitch (600-800lbs)