I have a 6x12 enclosed trailer and I cant seem to unhook the trailer off the ball with a full load. I have to unload my mowers which is costing me serious time. My storage unit is 24x33ft , but the floor is gravel so I was thinking that the trailer ball is not level with the trailer...could that be my problem? Someone told me to get a railroad tie and that might help. By the way its a single axel trailer... anyone have any input??