I would remove the fan belt by loosening the generator off first. Using an old screw driver, bend back the tab washer. Engage first gear and apply hand brake. Fit socket, maybe tap it firmly on to make sure tab washer is bent back as flat as possible, and undo. if necessary, slide a length of steel tubing over the handle of your tool for extra leverage. For the cost of a tab washer, I would fit new but if not available, K’s advice above would be ok.
