You can probably duplicate the problem by holding the brake on bouncing the forks. I would try to recreate the stiction in the garage then try to correct by loosening the brace, loosening the axle and pinch bolts, and bouncing the forks and see if there is a change. If not it may be internal. If it gets better I'd retighten wheel assembly and recheck. If better retighten the brace and recheck by the bounce test.