Pretty much the same thing happened to me when I restored mine. The cause is the bolt that's welded to the backside of the hinge bracket has probably broken. I removed one of the two bolts that would come apart & used that hole as access. I took a old bar, cut it to size to fit through the removed bolt hole, bent it to ninety degrees & then manuvered it to pinch the nut while a buddy loosened the bolt. The bad news is that the only way to properly fix it, is to remove the fender to gain access to re-weld the nut. Good Luck.
