Been several years since I had one off, but seem to remember that is unthreads righty tighty lefty loosy. So try hitting the left side of the blade bar with a hammer and see what happens.
#3
mattm55
Agreed. I held mine with the top nut and smacked it with a hammer as it does un-thread. I'm also not sure which way it tightens/loosens. There might be spacers underneath too..
